diff --git a/algorithms-miscellaneous-3/pom.xml b/algorithms-miscellaneous-3/pom.xml
index 525a2556de..11a64eba8b 100644
--- a/algorithms-miscellaneous-3/pom.xml
+++ b/algorithms-miscellaneous-3/pom.xml
@@ -37,7 +37,7 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
-            <version>${commons.lang3.version}</version>
+            <version>${commons-lang3.version}</version>
         </dependency>
         <dependency>
             <groupId>pl.pragmatists</groupId>
@@ -63,10 +63,8 @@
     </dependencies>
 
     <properties>
-        <commons-collections4.version>4.3</commons-collections4.version>
         <guava.version>28.0-jre</guava.version>
         <retrofit.version>2.6.0</retrofit.version>
-        <commons.lang3.version>3.8.1</commons.lang3.version>
         <JUnitParams.version>1.1.0</JUnitParams.version>
     </properties>
 
diff --git a/apache-poi-2/.gitignore b/apache-poi-2/.gitignore
new file mode 100644
index 0000000000..9552c1e63d
--- /dev/null
+++ b/apache-poi-2/.gitignore
@@ -0,0 +1,3 @@
+*.docx
+temp.xls
+temp.xlsx
diff --git a/apache-poi-2/README.md b/apache-poi-2/README.md
new file mode 100644
index 0000000000..69aabf4616
--- /dev/null
+++ b/apache-poi-2/README.md
@@ -0,0 +1,8 @@
+## Apache POI
+
+This module contains articles about Apache POI
+
+### Relevant Articles:
+
+- [Adding a Column to an Excel Sheet Using Apache POI](https://www.baeldung.com/java-excel-add-column)
+- More articles: [[<-- prev]](/apache-poi)
diff --git a/apache-poi-2/pom.xml b/apache-poi-2/pom.xml
new file mode 100644
index 0000000000..a46365c63c
--- /dev/null
+++ b/apache-poi-2/pom.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>apache-poi-2</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>apache-poi-2</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-ooxml</artifactId>
+            <version>${poi.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <poi.version>5.0.0</poi.version>
+    </properties>
+
+</project>
+
diff --git a/apache-poi-2/src/main/java/com/baeldung/poi/excel/newcolumn/ExcelColumn.java b/apache-poi-2/src/main/java/com/baeldung/poi/excel/newcolumn/ExcelColumn.java
new file mode 100644
index 0000000000..00ca24f6e8
--- /dev/null
+++ b/apache-poi-2/src/main/java/com/baeldung/poi/excel/newcolumn/ExcelColumn.java
@@ -0,0 +1,16 @@
+package com.baeldung.poi.excel.newcolumn;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+
+public class ExcelColumn {
+
+    public void addColumn(Sheet sheet, CellType cellType) {
+        for (Row currentRow : sheet) {
+            currentRow.createCell(currentRow.getLastCellNum(), cellType);
+        }
+    }
+}
diff --git a/apache-poi-2/src/main/java/com/baeldung/poi/excel/write/addimageincell/ExcelCellImageHelper.java b/apache-poi-2/src/main/java/com/baeldung/poi/excel/write/addimageincell/ExcelCellImageHelper.java
new file mode 100644
index 0000000000..6bd4f9d66b
--- /dev/null
+++ b/apache-poi-2/src/main/java/com/baeldung/poi/excel/write/addimageincell/ExcelCellImageHelper.java
@@ -0,0 +1,76 @@
+package com.baeldung.poi.excel.write.addimageincell;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.util.IOUtils;
+import org.apache.poi.xssf.usermodel.XSSFClientAnchor;
+import org.apache.poi.xssf.usermodel.XSSFDrawing;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+/**
+ * This Helper class Add an Image to a Cell of an Excel File With apache-poi api.
+ *
+ */
+public class ExcelCellImageHelper {
+
+    public static void main(String[] args) throws IOException, InvalidFormatException {
+        try (final Workbook workbook = new XSSFWorkbook();
+            FileOutputStream saveExcel = new FileOutputStream("target/baeldung-apachepoi.xlsx");) {
+            
+            Sheet sheet = workbook.createSheet("Avengers");
+
+            XSSFDrawing drawing = (XSSFDrawing) sheet.createDrawingPatriarch();
+            XSSFClientAnchor ironManAnchor = new XSSFClientAnchor();
+            XSSFClientAnchor spiderManAnchor = new XSSFClientAnchor();
+
+            // Fill row1 data
+            Row row1 = sheet.createRow(0);
+            row1.setHeight((short) 1000);
+            row1.createCell(0)
+                .setCellValue("IRON-MAN");
+            updateCellWithImage(workbook, 1, drawing, ironManAnchor, "ironman.png");
+
+            // Fill row2 data
+            Row row2 = sheet.createRow(1);
+            row2.setHeight((short) 1000);
+            row2.createCell(0)
+                .setCellValue("SPIDER-MAN");
+            updateCellWithImage(workbook, 2, drawing, spiderManAnchor, "spiderman.png");
+
+            // Resize all columns to fit the content size
+            for (int i = 0; i < 2; i++) {
+                sheet.autoSizeColumn(i);
+            }
+            workbook.write(saveExcel);
+        }
+
+    }
+
+    /**
+     * This method position the anchor for a given rowNum and add the image correctly.
+     * @param workbook
+     * @param rowNum
+     * @param drawing
+     * @param inputImageAnchor
+     * @throws IOException
+     */
+    private static void updateCellWithImage(Workbook workbook, int rowNum, XSSFDrawing drawing, XSSFClientAnchor inputImageAnchor, String inputImageName) throws IOException {
+        InputStream inputImageStream = ExcelCellImageHelper.class.getClassLoader()
+            .getResourceAsStream(inputImageName);
+        byte[] inputImageBytes = IOUtils.toByteArray(inputImageStream);
+        int inputImagePictureID = workbook.addPicture(inputImageBytes, Workbook.PICTURE_TYPE_PNG);
+        inputImageStream.close();
+        inputImageAnchor.setCol1(1);
+        inputImageAnchor.setRow1(rowNum - 1);
+        inputImageAnchor.setCol2(2);
+        inputImageAnchor.setRow2(rowNum);
+        drawing.createPicture(inputImageAnchor, inputImagePictureID);
+    }
+
+}
diff --git a/apache-poi-2/src/main/resources/ironman.png b/apache-poi-2/src/main/resources/ironman.png
new file mode 100644
index 0000000000..30096294c9
Binary files /dev/null and b/apache-poi-2/src/main/resources/ironman.png differ
diff --git a/apache-poi-2/src/main/resources/spiderman.png b/apache-poi-2/src/main/resources/spiderman.png
new file mode 100644
index 0000000000..32982bbe65
Binary files /dev/null and b/apache-poi-2/src/main/resources/spiderman.png differ
diff --git a/apache-poi-2/src/test/java/com/baeldung/poi/excel/newcolumn/ExcelColumnUnitTest.java b/apache-poi-2/src/test/java/com/baeldung/poi/excel/newcolumn/ExcelColumnUnitTest.java
new file mode 100644
index 0000000000..9b991719b1
--- /dev/null
+++ b/apache-poi-2/src/test/java/com/baeldung/poi/excel/newcolumn/ExcelColumnUnitTest.java
@@ -0,0 +1,40 @@
+package com.baeldung.poi.excel.newcolumn;
+
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import static org.junit.Assert.assertEquals;
+
+public class ExcelColumnUnitTest {
+    private static final String FILE_NAME = "newColumnTest.xlsx";
+    private String fileLocation;
+
+    @Before
+    public void setup() throws URISyntaxException {
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+    }
+
+    @Test
+    public void givenExistingRows_whenAddNewColumn_thenRowColumnNumberIncreased() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+        assertEquals(5, row.getLastCellNum());
+
+        ExcelColumn excelColumn = new ExcelColumn();
+        excelColumn.addColumn(sheet, CellType.STRING);
+        assertEquals(6, row.getLastCellNum());
+
+        workbook.close();
+    }
+
+}
\ No newline at end of file
diff --git a/apache-poi-2/src/test/resources/newColumnTest.xlsx b/apache-poi-2/src/test/resources/newColumnTest.xlsx
new file mode 100644
index 0000000000..54e8734d58
Binary files /dev/null and b/apache-poi-2/src/test/resources/newColumnTest.xlsx differ
diff --git a/apache-poi/README.md b/apache-poi/README.md
index d3d60358c5..6d5b80b03a 100644
--- a/apache-poi/README.md
+++ b/apache-poi/README.md
@@ -15,3 +15,4 @@ This module contains articles about Apache POI
 - [Multiline Text in Excel Cell Using Apache POI](https://www.baeldung.com/apache-poi-write-multiline-text)
 - [Set Background Color of a Cell with Apache POI](https://www.baeldung.com/apache-poi-background-color)
 - [Add Borders to Excel Cells With Apache POI](https://www.baeldung.com/apache-poi-add-borders)
+- More articles: [[next -->]](/apache-poi-2)
diff --git a/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java b/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java
new file mode 100644
index 0000000000..50bbfbbe3c
--- /dev/null
+++ b/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java
@@ -0,0 +1,75 @@
+package com.baeldung.poi.excel;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.DateUtil;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+public class ExcelUtility {
+    private static final String ENDLINE = System.getProperty("line.separator");
+
+    public static String readExcel(String filePath) throws IOException {
+        File file = new File(filePath);
+        FileInputStream inputStream = null;
+        StringBuilder toReturn = new StringBuilder();
+        try {
+            inputStream = new FileInputStream(file);
+            Workbook baeuldungWorkBook = new XSSFWorkbook(inputStream);
+            for (Sheet sheet : baeuldungWorkBook) {
+                toReturn.append("--------------------------------------------------------------------")
+                    .append(ENDLINE);
+                toReturn.append("Worksheet :")
+                    .append(sheet.getSheetName())
+                    .append(ENDLINE);
+                toReturn.append("--------------------------------------------------------------------")
+                    .append(ENDLINE);
+                int firstRow = sheet.getFirstRowNum();
+                int lastRow = sheet.getLastRowNum();
+                for (int index = firstRow + 1; index <= lastRow; index++) {
+                    Row row = sheet.getRow(index);
+                    toReturn.append("|| ");
+                    for (int cellIndex = row.getFirstCellNum(); cellIndex < row.getLastCellNum(); cellIndex++) {
+                        Cell cell = row.getCell(cellIndex, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK);
+                        printCellValue(cell, toReturn);
+                    }
+                    toReturn.append(" ||")
+                        .append(ENDLINE);
+                }
+            }
+            inputStream.close();
+
+        } catch (IOException e) {
+            throw e;
+        }
+        return toReturn.toString();
+    }
+
+    public static void printCellValue(Cell cell, StringBuilder toReturn) {
+        CellType cellType = cell.getCellType()
+            .equals(CellType.FORMULA) ? cell.getCachedFormulaResultType() : cell.getCellType();
+        if (cellType.equals(CellType.STRING)) {
+            toReturn.append(cell.getStringCellValue())
+                .append(" | ");
+        }
+        if (cellType.equals(CellType.NUMERIC)) {
+            if (DateUtil.isCellDateFormatted(cell)) {
+                toReturn.append(cell.getDateCellValue())
+                    .append(" | ");
+            } else {
+                toReturn.append(cell.getNumericCellValue())
+                    .append(" | ");
+            }
+        }
+        if (cellType.equals(CellType.BOOLEAN)) {
+            toReturn.append(cell.getBooleanCellValue())
+                .append(" | ");
+        }
+    }
+}
\ No newline at end of file
diff --git a/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java.orig b/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java.orig
new file mode 100644
index 0000000000..c058f3abcf
--- /dev/null
+++ b/apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java.orig
@@ -0,0 +1,128 @@
+package com.baeldung.poi.excel;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.DateUtil;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+public class ExcelUtility {
+<<<<<<< HEAD
+    private static final String ENDLINE = System.getProperty("line.separator");
+
+    public static String readExcel(String filePath) throws IOException {
+        File file = new File(filePath);
+        FileInputStream inputStream = null;
+        StringBuilder toReturn = new StringBuilder();
+        try {
+            inputStream = new FileInputStream(file);
+            Workbook baeuldungWorkBook = new XSSFWorkbook(inputStream);
+            for (Sheet sheet : baeuldungWorkBook) {
+                toReturn.append("--------------------------------------------------------------------")
+                    .append(ENDLINE);
+                toReturn.append("Worksheet :")
+                    .append(sheet.getSheetName())
+                    .append(ENDLINE);
+                toReturn.append("--------------------------------------------------------------------")
+                    .append(ENDLINE);
+                int firstRow = sheet.getFirstRowNum();
+                int lastRow = sheet.getLastRowNum();
+                for (int index = firstRow + 1; index <= lastRow; index++) {
+                    Row row = sheet.getRow(index);
+                    toReturn.append("|| ");
+                    for (int cellIndex = row.getFirstCellNum(); cellIndex < row.getLastCellNum(); cellIndex++) {
+                        Cell cell = row.getCell(cellIndex, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK);
+                        printCellValue(cell, toReturn);
+                    }
+                    toReturn.append(" ||")
+                        .append(ENDLINE);
+                }
+            }
+            inputStream.close();
+
+        } catch (IOException e) {
+            throw e;
+        }
+        return toReturn.toString();
+    }
+
+    public static void printCellValue(Cell cell, StringBuilder toReturn) {
+        CellType cellType = cell.getCellType()
+            .equals(CellType.FORMULA) ? cell.getCachedFormulaResultType() : cell.getCellType();
+        if (cellType.equals(CellType.STRING)) {
+            toReturn.append(cell.getStringCellValue())
+                .append(" | ");
+        }
+        if (cellType.equals(CellType.NUMERIC)) {
+            if (DateUtil.isCellDateFormatted(cell)) {
+                toReturn.append(cell.getDateCellValue())
+                    .append(" | ");
+            } else {
+                toReturn.append(cell.getNumericCellValue())
+                    .append(" | ");
+            }
+        }
+        if (cellType.equals(CellType.BOOLEAN)) {
+            toReturn.append(cell.getBooleanCellValue())
+                .append(" | ");
+        }
+    }
+=======
+	private static final String ENDLINE = System.getProperty("line.separator");
+
+	public static String readExcel(String filePath) throws IOException {
+		File file = new File(filePath);
+		FileInputStream inputStream = null;
+		StringBuilder toReturn = new StringBuilder();
+		try {
+			inputStream = new FileInputStream(file);
+			Workbook baeuldungWorkBook = new XSSFWorkbook(inputStream);
+			for (Sheet sheet : baeuldungWorkBook) {
+				toReturn.append("--------------------------------------------------------------------").append(ENDLINE);
+				toReturn.append("Worksheet :").append(sheet.getSheetName()).append(ENDLINE);
+				toReturn.append("--------------------------------------------------------------------").append(ENDLINE);
+				int firstRow = sheet.getFirstRowNum();
+				int lastRow = sheet.getLastRowNum();
+				for (int index = firstRow + 1; index <= lastRow; index++) {
+					Row row = sheet.getRow(index);
+					toReturn.append("|| ");
+					for (int cellIndex = row.getFirstCellNum(); cellIndex < row.getLastCellNum(); cellIndex++) {
+						Cell cell = row.getCell(cellIndex, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK);
+						printCellValue(cell, toReturn);
+					}
+					toReturn.append(" ||").append(ENDLINE);
+				}
+			}
+			inputStream.close();
+
+		} catch (IOException e) {
+			throw e;
+		}
+		return toReturn.toString();
+	}
+
+	public static void printCellValue(Cell cell, StringBuilder toReturn) {
+		CellType cellType = cell.getCellType().equals(CellType.FORMULA) ? cell.getCachedFormulaResultType()
+				: cell.getCellType();
+		if (cellType.equals(CellType.STRING)) {
+			toReturn.append(cell.getStringCellValue()).append(" | ");
+		}
+		if (cellType.equals(CellType.NUMERIC)) {
+			if (DateUtil.isCellDateFormatted(cell)) {
+				toReturn.append(cell.getDateCellValue()).append(" | ");
+			} else {
+				toReturn.append(cell.getNumericCellValue()).append(" | ");
+			}
+		}
+		if (cellType.equals(CellType.BOOLEAN)) {
+			toReturn.append(cell.getBooleanCellValue()).append(" | ");
+		}
+	}
+>>>>>>> master
+}
\ No newline at end of file
diff --git a/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java b/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java
new file mode 100644
index 0000000000..b4d3fdd732
--- /dev/null
+++ b/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java
@@ -0,0 +1,72 @@
+package com.baeldung.poi.excel;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExcelUtilityUnitTest {
+    private static final String FILE_NAME = "baeldung.xlsx";
+    private String fileLocation;
+    private static final String ENDLINE = System.getProperty("line.separator");
+    private StringBuilder output;
+
+    @Before
+    public void setupUnitTest() throws IOException, URISyntaxException, ParseException {
+        output = new StringBuilder();
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("Worksheet :Sheet1")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("|| Name1 | Surname1 | 3.55696564113E11 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021")
+                .toString())
+            .append(" | ‡ |  ||")
+            .append(ENDLINE);
+        output.append("|| Name2 | Surname2 | 5.646513512E9 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/12/2021")
+                .toString())
+            .append(" | false |  ||")
+            .append(ENDLINE);
+        output.append("|| Name3 | Surname3 | 3.55696564113E11 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021")
+                .toString())
+            .append(" | 7.17039641738E11 |  ||")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("Worksheet :Sheet2")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("|| Name4 | Surname4 | 3.55675623232E11 | 13/04/2021 |  ||")
+            .append(ENDLINE);
+
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME)
+            .toURI())
+            .toString();
+    }
+
+    @Test
+    public void givenStringPath_whenReadExcel_thenReturnStringValue() throws IOException {
+        assertEquals(output.toString(), ExcelUtility.readExcel(fileLocation));
+
+    }
+
+    @Test
+    public void givenStringPath_whenReadExcel_thenThrowException() {
+        assertThrows(IOException.class, () -> {
+            ExcelUtility.readExcel("baeldung");
+        });
+    }
+
+}
diff --git a/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java.orig b/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java.orig
new file mode 100644
index 0000000000..cfc3062b5a
--- /dev/null
+++ b/apache-poi/src/test/java/com/baeldung/poi/excel/ExcelUtilityUnitTest.java.orig
@@ -0,0 +1,112 @@
+package com.baeldung.poi.excel;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExcelUtilityUnitTest {
+<<<<<<< HEAD
+    private static final String FILE_NAME = "baeldung.xlsx";
+    private String fileLocation;
+    private static final String ENDLINE = System.getProperty("line.separator");
+    private StringBuilder output;
+
+    @Before
+    public void setupUnitTest() throws IOException, URISyntaxException, ParseException {
+        output = new StringBuilder();
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("Worksheet :Sheet1")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("|| Name1 | Surname1 | 3.55696564113E11 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021")
+                .toString())
+            .append(" | ‡ |  ||")
+            .append(ENDLINE);
+        output.append("|| Name2 | Surname2 | 5.646513512E9 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/12/2021")
+                .toString())
+            .append(" | false |  ||")
+            .append(ENDLINE);
+        output.append("|| Name3 | Surname3 | 3.55696564113E11 | ")
+            .append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021")
+                .toString())
+            .append(" | 7.17039641738E11 |  ||")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("Worksheet :Sheet2")
+            .append(ENDLINE);
+        output.append("--------------------------------------------------------------------")
+            .append(ENDLINE);
+        output.append("|| Name4 | Surname4 | 3.55675623232E11 | 13/04/2021 |  ||")
+            .append(ENDLINE);
+
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME)
+            .toURI())
+            .toString();
+    }
+
+    @Test
+    public void givenStringPath_whenReadExcel_thenReturnStringValue() throws IOException {
+        assertEquals(output.toString(), ExcelUtility.readExcel(fileLocation));
+
+    }
+
+    @Test
+    public void givenStringPath_whenReadExcel_thenThrowException() {
+        assertThrows(IOException.class, () -> {
+            ExcelUtility.readExcel("baeldung");
+        });
+    }
+=======
+	private static final String FILE_NAME = "baeldung.xlsx";
+	private String fileLocation;
+	private static final String ENDLINE = System.getProperty("line.separator");
+	private StringBuilder output;
+
+	@Before
+	public void setupUnitTest() throws IOException, URISyntaxException, ParseException {
+		output = new StringBuilder();
+		output.append("--------------------------------------------------------------------").append(ENDLINE);
+		output.append("Worksheet :Sheet1").append(ENDLINE);
+		output.append("--------------------------------------------------------------------").append(ENDLINE);
+		output.append("|| Name1 | Surname1 | 3.55696564113E11 | ").append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021").toString()).append(" | ‡ |  ||")
+				.append(ENDLINE);
+		output.append("|| Name2 | Surname2 | 5.646513512E9 | ").append(new SimpleDateFormat("dd/MM/yyyy").parse("4/12/2021").toString()).append(" | false |  ||")
+				.append(ENDLINE);
+		output.append("|| Name3 | Surname3 | 3.55696564113E11 | ").append(new SimpleDateFormat("dd/MM/yyyy").parse("4/11/2021").toString()).append(" | 7.17039641738E11 |  ||")
+				.append(ENDLINE);
+		output.append("--------------------------------------------------------------------").append(ENDLINE);
+		output.append("Worksheet :Sheet2").append(ENDLINE);
+		output.append("--------------------------------------------------------------------").append(ENDLINE);
+		output.append("|| Name4 | Surname4 | 3.55675623232E11 | 13/04/2021 |  ||").append(ENDLINE);
+
+		fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+	}
+
+	@Test
+	public void givenStringPath_whenReadExcel_thenReturnStringValue() throws IOException {
+		assertEquals(output.toString(), ExcelUtility.readExcel(fileLocation));
+
+	}
+
+	@Test
+	public void givenStringPath_whenReadExcel_thenThrowException() {
+		assertThrows(IOException.class, () -> {
+			ExcelUtility.readExcel("baeldung");
+		});
+	}
+>>>>>>> master
+
+}
diff --git a/apache-poi/src/test/resources/baeldung.xlsx b/apache-poi/src/test/resources/baeldung.xlsx
new file mode 100644
index 0000000000..a6ed6c4e6a
Binary files /dev/null and b/apache-poi/src/test/resources/baeldung.xlsx differ
diff --git a/core-java-modules/core-java-10/pom.xml b/core-java-modules/core-java-10/pom.xml
index c3406751dc..e2ac8db919 100644
--- a/core-java-modules/core-java-10/pom.xml
+++ b/core-java-modules/core-java-10/pom.xml
@@ -39,7 +39,6 @@
     <properties>
         <maven.compiler.source.version>10</maven.compiler.source.version>
         <maven.compiler.target.version>10</maven.compiler.target.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-11-2/pom.xml b/core-java-modules/core-java-11-2/pom.xml
index 332b24ff2e..b077373448 100644
--- a/core-java-modules/core-java-11-2/pom.xml
+++ b/core-java-modules/core-java-11-2/pom.xml
@@ -12,6 +12,7 @@
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../pom.xml</relativePath>
     </parent>
 
     <dependencies>
@@ -35,18 +36,6 @@
             <artifactId>jakarta.xml.ws-api</artifactId>
             <version>${jakarta.ws-api.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.sun.xml.ws</groupId>
-            <artifactId>jaxws-rt</artifactId>
-            <version>${jaxws-rt.version}</version>
-            <scope>runtime</scope>
-        </dependency>
-        <dependency>
-            <groupId>com.sun.xml.ws</groupId>
-            <artifactId>jaxws-ri</artifactId>
-            <version>${jaxws-ri.version}</version>
-            <type>pom</type>
-        </dependency>
     </dependencies>
 
     <build>
@@ -82,10 +71,8 @@
         <maven.compiler.target.version>11</maven.compiler.target.version>
         <guava.version>29.0-jre</guava.version>
         <mockserver.version>5.11.1</mockserver.version>
-        <jakarta.ws-api.version>3.0.0</jakarta.ws-api.version>
-        <jaxws-rt.version>3.0.0</jaxws-rt.version>
-        <jaxws-ri.version>2.3.1</jaxws-ri.version>
-        <jaxws-maven-plugin.version>2.3.2</jaxws-maven-plugin.version>
+        <jakarta.ws-api.version>3.0.1</jakarta.ws-api.version>
+        <jaxws-maven-plugin.version>3.0.2</jaxws-maven-plugin.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Country.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Country.java
index 950d588661..d39f333b41 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Country.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Country.java
@@ -1,10 +1,10 @@
 
 package com.baeldung.soap.ws.client.generated;
 
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-import javax.xml.bind.annotation.XmlSchemaType;
-import javax.xml.bind.annotation.XmlType;
+import jakarta.xml.bind.annotation.XmlAccessType;
+import jakarta.xml.bind.annotation.XmlAccessorType;
+import jakarta.xml.bind.annotation.XmlSchemaType;
+import jakarta.xml.bind.annotation.XmlType;
 
 
 /**
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryService.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryService.java
index 807d152cf1..f10dcade1b 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryService.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryService.java
@@ -1,19 +1,19 @@
 
 package com.baeldung.soap.ws.client.generated;
 
-import javax.jws.WebMethod;
-import javax.jws.WebParam;
-import javax.jws.WebResult;
-import javax.jws.WebService;
-import javax.jws.soap.SOAPBinding;
-import javax.xml.bind.annotation.XmlSeeAlso;
-import javax.xml.ws.Action;
+import jakarta.jws.WebMethod;
+import jakarta.jws.WebParam;
+import jakarta.jws.WebResult;
+import jakarta.jws.WebService;
+import jakarta.jws.soap.SOAPBinding;
+import jakarta.xml.bind.annotation.XmlSeeAlso;
+import jakarta.xml.ws.Action;
 
 
 /**
  * This class was generated by the JAX-WS RI.
- * JAX-WS RI 2.3.2
- * Generated source version: 2.2
+ * JAX-WS RI 3.0.2
+ * Generated source version: 3.0
  * 
  */
 @WebService(name = "CountryService", targetNamespace = "http://server.ws.soap.baeldung.com/")
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryServiceImplService.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryServiceImplService.java
index 97d6c82145..ae7ff38f7d 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryServiceImplService.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/CountryServiceImplService.java
@@ -4,17 +4,17 @@ package com.baeldung.soap.ws.client.generated;
 import java.net.MalformedURLException;
 import java.net.URL;
 import javax.xml.namespace.QName;
-import javax.xml.ws.Service;
-import javax.xml.ws.WebEndpoint;
-import javax.xml.ws.WebServiceClient;
-import javax.xml.ws.WebServiceException;
-import javax.xml.ws.WebServiceFeature;
+import jakarta.xml.ws.Service;
+import jakarta.xml.ws.WebEndpoint;
+import jakarta.xml.ws.WebServiceClient;
+import jakarta.xml.ws.WebServiceException;
+import jakarta.xml.ws.WebServiceFeature;
 
 
 /**
  * This class was generated by the JAX-WS RI.
- * JAX-WS RI 2.3.2
- * Generated source version: 2.2
+ * JAX-WS RI 3.0.2
+ * Generated source version: 3.0
  * 
  */
 @WebServiceClient(name = "CountryServiceImplService", targetNamespace = "http://server.ws.soap.baeldung.com/", wsdlLocation = "http://localhost:8888/ws/country?wsdl")
@@ -75,7 +75,7 @@ public class CountryServiceImplService
     /**
      * 
      * @param features
-     *     A list of {@link javax.xml.ws.WebServiceFeature} to configure on the proxy.  Supported features not in the <code>features</code> parameter will have their default values.
+     *     A list of {@link jakarta.xml.ws.WebServiceFeature} to configure on the proxy.  Supported features not in the <code>features</code> parameter will have their default values.
      * @return
      *     returns CountryService
      */
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Currency.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Currency.java
index c010f5533c..ad42c65461 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Currency.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/Currency.java
@@ -1,15 +1,14 @@
 
 package com.baeldung.soap.ws.client.generated;
 
-import javax.xml.bind.annotation.XmlEnum;
-import javax.xml.bind.annotation.XmlType;
+import jakarta.xml.bind.annotation.XmlEnum;
+import jakarta.xml.bind.annotation.XmlType;
 
 
 /**
  * <p>Java class for currency.
  * 
  * <p>The following schema fragment specifies the expected content contained within this class.
- * <p>
  * <pre>
  * &lt;simpleType name="currency"&gt;
  *   &lt;restriction base="{http://www.w3.org/2001/XMLSchema}string"&gt;
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/ObjectFactory.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/ObjectFactory.java
index 9ed85fe2b9..0489e49c2b 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/ObjectFactory.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/ObjectFactory.java
@@ -1,7 +1,7 @@
 
 package com.baeldung.soap.ws.client.generated;
 
-import javax.xml.bind.annotation.XmlRegistry;
+import jakarta.xml.bind.annotation.XmlRegistry;
 
 
 /**
diff --git a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/package-info.java b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/package-info.java
index dfc556859f..6dcc08c268 100644
--- a/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/package-info.java
+++ b/core-java-modules/core-java-11-2/src/main/java/com/baeldung/soap/ws/client/generated/package-info.java
@@ -1,2 +1,2 @@
-@javax.xml.bind.annotation.XmlSchema(namespace = "http://server.ws.soap.baeldung.com/")
+@jakarta.xml.bind.annotation.XmlSchema(namespace = "http://server.ws.soap.baeldung.com/")
 package com.baeldung.soap.ws.client.generated;
diff --git a/core-java-modules/core-java-11/pom.xml b/core-java-modules/core-java-11/pom.xml
index fc61e373ec..1fa5ae2b45 100644
--- a/core-java-modules/core-java-11/pom.xml
+++ b/core-java-modules/core-java-11/pom.xml
@@ -13,6 +13,8 @@
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
+
+        <relativePath>../../pom.xml</relativePath>
     </parent>
 
     <dependencies>
diff --git a/core-java-modules/core-java-8/pom.xml b/core-java-modules/core-java-8/pom.xml
index 85e289280b..89925bdbbb 100644
--- a/core-java-modules/core-java-8/pom.xml
+++ b/core-java-modules/core-java-8/pom.xml
@@ -43,9 +43,4 @@
         </resources>
     </build>
 
-    <properties>
-        <!-- util -->
-        <commons-collections4.version>4.1</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-9/pom.xml b/core-java-modules/core-java-9/pom.xml
index 03a097e7a9..274d9ccb43 100644
--- a/core-java-modules/core-java-9/pom.xml
+++ b/core-java-modules/core-java-9/pom.xml
@@ -76,7 +76,6 @@
         <maven.compiler.source>1.9</maven.compiler.source>
         <maven.compiler.target>1.9</maven.compiler.target>
         <guava.version>25.1-jre</guava.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-2/pom.xml b/core-java-modules/core-java-collections-2/pom.xml
index 23100b1d87..e78f7b5dda 100644
--- a/core-java-modules/core-java-collections-2/pom.xml
+++ b/core-java-modules/core-java-collections-2/pom.xml
@@ -44,7 +44,6 @@
 
     <properties>
         <eclipse.collections.version>7.1.0</eclipse.collections.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <commons-exec.version>1.3</commons-exec.version>
     </properties>
 
diff --git a/core-java-modules/core-java-collections-3/README.md b/core-java-modules/core-java-collections-3/README.md
index 6bc9139856..4249d8ad30 100644
--- a/core-java-modules/core-java-collections-3/README.md
+++ b/core-java-modules/core-java-collections-3/README.md
@@ -11,7 +11,7 @@
 - [Performance of contains() in a HashSet vs ArrayList](https://www.baeldung.com/java-hashset-arraylist-contains-performance)
 - [Fail-Safe Iterator vs Fail-Fast Iterator](https://www.baeldung.com/java-fail-safe-vs-fail-fast-iterator)
 - [Quick Guide to the Java Stack](https://www.baeldung.com/java-stack)
-- [Convert an Array of Primitives to a List](https://www.baeldung.com/java-primitive-array-to-list)
 - [A Guide to BitSet in Java](https://www.baeldung.com/java-bitset)
 - [Get the First Key and Value From a HashMap](https://www.baeldung.com/java-hashmap-get-first-entry)
 - [Performance of removeAll() in a HashSet](https://www.baeldung.com/java-hashset-removeall-performance)
+- More articles: [[<-- prev]](/core-java-modules/core-java-collections-2) [[next -->]](/core-java-modules/core-java-collections-4)
diff --git a/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/stack/StackUnitTest.java b/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/stack/StackUnitTest.java
index 6a2feff551..14eafe8924 100644
--- a/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/stack/StackUnitTest.java
+++ b/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/stack/StackUnitTest.java
@@ -1,4 +1,4 @@
-package com.baeldung.stack;
+package com.baeldung.collections.stack;
 
 import org.junit.Test;
 
diff --git a/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/DynamicTypeValue.java b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/DynamicTypeValue.java
new file mode 100644
index 0000000000..4c9ed89f63
--- /dev/null
+++ b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/DynamicTypeValue.java
@@ -0,0 +1,5 @@
+package com.baeldung.collections.mulipletypesinmap;
+
+public interface DynamicTypeValue {
+    String valueDescription();
+}
diff --git a/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/InstantTypeValue.java b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/InstantTypeValue.java
new file mode 100644
index 0000000000..448e66d872
--- /dev/null
+++ b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/InstantTypeValue.java
@@ -0,0 +1,24 @@
+package com.baeldung.collections.mulipletypesinmap;
+
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+
+public class InstantTypeValue implements DynamicTypeValue {
+    private static DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
+        .withZone(ZoneId.systemDefault());
+    private Instant value;
+
+    public InstantTypeValue(Instant value) {
+        this.value = value;
+    }
+
+    @Override
+    public String valueDescription() {
+        if (value == null) {
+            return "The value is null.";
+        }
+        return String.format("The value is an instant: %s", FORMATTER.format(value));
+    }
+
+}
diff --git a/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntArrayTypeValue.java b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntArrayTypeValue.java
new file mode 100644
index 0000000000..290982183f
--- /dev/null
+++ b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntArrayTypeValue.java
@@ -0,0 +1,20 @@
+package com.baeldung.collections.mulipletypesinmap;
+
+import java.util.Arrays;
+
+public class IntArrayTypeValue implements DynamicTypeValue {
+    private int[] value;
+
+    public IntArrayTypeValue(int[] value) {
+        this.value = value;
+    }
+
+    @Override
+    public String valueDescription() {
+        if (value == null) {
+            return "The value is null.";
+        }
+        return String.format("The value is an array of %d integers: %s", value.length, Arrays.toString(value));
+    }
+
+}
diff --git a/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntegerTypeValue.java b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntegerTypeValue.java
new file mode 100644
index 0000000000..463b06f768
--- /dev/null
+++ b/core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/mulipletypesinmap/IntegerTypeValue.java
@@ -0,0 +1,17 @@
+package com.baeldung.collections.mulipletypesinmap;
+
+public class IntegerTypeValue implements DynamicTypeValue {
+    private Integer value;
+
+    public IntegerTypeValue(Integer value) {
+        this.value = value;
+    }
+
+    @Override
+    public String valueDescription() {
+        if(value == null){
+            return "The value is null.";
+        }
+        return String.format("The value is a %s integer: %d", value > 0 ? "positive" : "negative", value);
+    }
+}
diff --git a/core-java-modules/core-java-collections-4/src/test/java/com/baeldung/multipletypesinmap/MultipleTypesInMapUnitTest.java b/core-java-modules/core-java-collections-4/src/test/java/com/baeldung/multipletypesinmap/MultipleTypesInMapUnitTest.java
new file mode 100644
index 0000000000..87ea310ab0
--- /dev/null
+++ b/core-java-modules/core-java-collections-4/src/test/java/com/baeldung/multipletypesinmap/MultipleTypesInMapUnitTest.java
@@ -0,0 +1,75 @@
+package com.baeldung.multipletypesinmap;
+
+import com.baeldung.collections.mulipletypesinmap.DynamicTypeValue;
+import com.baeldung.collections.mulipletypesinmap.InstantTypeValue;
+import com.baeldung.collections.mulipletypesinmap.IntArrayTypeValue;
+import com.baeldung.collections.mulipletypesinmap.IntegerTypeValue;
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class MultipleTypesInMapUnitTest {
+    private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
+        .withZone(ZoneId.systemDefault());
+
+    private static final Integer intValue = 777;
+    private static final int[] intArray = new int[]{2, 3, 5, 7, 11, 13};
+    private static final Instant instant = Instant.now();
+
+    private static final String KEY_INT = "E1 (Integer)";
+    private static final String KEY_INT_ARRAY = "E2 (IntArray)";
+    private static final String KEY_INSTANT = "E3 (Instant)";
+
+    @Test
+    void givenThreeTypes_whenUsingRawMap_thenPrintDescription() {
+        Map<String, Object> rawMap = new HashMap<>();
+        rawMap.put(KEY_INT, intValue);
+        rawMap.put(KEY_INT_ARRAY, intArray);
+        rawMap.put(KEY_INSTANT, instant);
+
+        rawMap.forEach((k, v) -> {
+            if (v instanceof Integer) {
+                Integer theV = (Integer) v;
+                String desc = String.format("The value is a %s integer: %d", theV > 0 ? "positive" : "negative", theV);
+                System.out.println(k + " -> " + desc);
+                assertThat(k).isEqualTo(KEY_INT);
+                assertThat(desc).isEqualTo("The value is a positive integer: 777");
+            } else if (v instanceof int[]) {
+                int[] theV = (int[]) v;
+                String desc = String.format("The value is an array of %d integers: %s", theV.length, Arrays.toString(theV));
+                System.out.println(k + " -> " + desc);
+                assertThat(k).isEqualTo(KEY_INT_ARRAY);
+                assertThat(desc).isEqualTo("The value is an array of 6 integers: [2, 3, 5, 7, 11, 13]");
+            } else if (v instanceof Instant) {
+                Instant theV = (Instant) v;
+                String desc = String.format("The value is an instant: %s", FORMATTER.format(theV));
+                System.out.println(k + " -> " + desc);
+                assertThat(k).isEqualTo(KEY_INSTANT);
+                assertThat(desc).matches("^The value is an instant: \\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}");
+            } else {
+                throw new IllegalStateException("Unknown Type found.");
+            }
+        });
+    }
+
+    @Test
+    void givenThreeTypes_whenUsingAnInterface_thenPrintDescription() {
+        Map<String, DynamicTypeValue> theMap = new HashMap<>();
+        theMap.put(KEY_INT, new IntegerTypeValue(intValue));
+        theMap.put(KEY_INT_ARRAY, new IntArrayTypeValue(intArray));
+        theMap.put(KEY_INSTANT, new InstantTypeValue(instant));
+
+        theMap.forEach((k, v) -> System.out.println(k + " -> " + v.valueDescription()));
+
+        assertThat(theMap.get(KEY_INT).valueDescription()).isEqualTo("The value is a positive integer: 777");
+        assertThat(theMap.get(KEY_INT_ARRAY).valueDescription()).isEqualTo("The value is an array of 6 integers: [2, 3, 5, 7, 11, 13]");
+        assertThat(theMap.get(KEY_INSTANT).valueDescription()).matches("^The value is an instant: \\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}");
+    }
+}
diff --git a/core-java-modules/core-java-collections-array-list/pom.xml b/core-java-modules/core-java-collections-array-list/pom.xml
index ca9c173947..6b040739e8 100644
--- a/core-java-modules/core-java-collections-array-list/pom.xml
+++ b/core-java-modules/core-java-collections-array-list/pom.xml
@@ -22,8 +22,4 @@
         </dependency>
     </dependencies>
 
-    <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-list-2/pom.xml b/core-java-modules/core-java-collections-list-2/pom.xml
index 7876b19cf9..59ab8c5f27 100644
--- a/core-java-modules/core-java-collections-list-2/pom.xml
+++ b/core-java-modules/core-java-collections-list-2/pom.xml
@@ -28,8 +28,4 @@
         </dependency>
     </dependencies>
 
-    <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-list-3/pom.xml b/core-java-modules/core-java-collections-list-3/pom.xml
index 9238939df7..3bb0fb4a33 100644
--- a/core-java-modules/core-java-collections-list-3/pom.xml
+++ b/core-java-modules/core-java-collections-list-3/pom.xml
@@ -54,7 +54,6 @@
     </dependencies>
 
     <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <trove4j.version>3.0.2</trove4j.version>
         <fastutil.version>8.1.0</fastutil.version>
         <colt.version>1.2.0</colt.version>
diff --git a/core-java-modules/core-java-collections-list/pom.xml b/core-java-modules/core-java-collections-list/pom.xml
index b60906d1ba..0cc8828a0d 100644
--- a/core-java-modules/core-java-collections-list/pom.xml
+++ b/core-java-modules/core-java-collections-list/pom.xml
@@ -27,8 +27,4 @@
         </dependency>
     </dependencies>
 
-    <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-maps-2/pom.xml b/core-java-modules/core-java-collections-maps-2/pom.xml
index 060796fafa..36b15c24d5 100644
--- a/core-java-modules/core-java-collections-maps-2/pom.xml
+++ b/core-java-modules/core-java-collections-maps-2/pom.xml
@@ -55,7 +55,6 @@
 
     <properties>
         <streamex.version>0.6.5</streamex.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <avaitility.version>1.7.0</avaitility.version>
         <eclipse-collections.version>8.2.0</eclipse-collections.version>
         <hppc.version>0.7.2</hppc.version>
diff --git a/core-java-modules/core-java-collections-maps/pom.xml b/core-java-modules/core-java-collections-maps/pom.xml
index 66aca9c1b2..34b878df53 100644
--- a/core-java-modules/core-java-collections-maps/pom.xml
+++ b/core-java-modules/core-java-collections-maps/pom.xml
@@ -22,8 +22,4 @@
         </dependency>
     </dependencies>
 
-    <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-set/pom.xml b/core-java-modules/core-java-collections-set/pom.xml
index 359c0fc86f..0b6e324c78 100644
--- a/core-java-modules/core-java-collections-set/pom.xml
+++ b/core-java-modules/core-java-collections-set/pom.xml
@@ -49,7 +49,6 @@
     <properties>
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
-        <commons-collections4.version>4.3</commons-collections4.version>
         <gson.version>2.8.5</gson.version>
     </properties>
 
diff --git a/core-java-modules/core-java-collections/README.md b/core-java-modules/core-java-collections/README.md
index 12e3c5ac17..574f61ac6a 100644
--- a/core-java-modules/core-java-collections/README.md
+++ b/core-java-modules/core-java-collections/README.md
@@ -12,4 +12,5 @@ This module contains articles about Java collections
 - [Defining a Char Stack in Java](https://www.baeldung.com/java-char-stack)
 - [Guide to the Java Queue Interface](https://www.baeldung.com/java-queue)
 - [An Introduction to Synchronized Java Collections](https://www.baeldung.com/java-synchronized-collections)
-- [[More -->]](/core-java-modules/core-java-collections-2)
+- [Convert an Array of Primitives to a List](https://www.baeldung.com/java-primitive-array-to-list)
+- More articles: [[next -->]](/core-java-modules/core-java-collections-2)
diff --git a/core-java-modules/core-java-collections/pom.xml b/core-java-modules/core-java-collections/pom.xml
index 8df0d7cdd3..eab7a35584 100644
--- a/core-java-modules/core-java-collections/pom.xml
+++ b/core-java-modules/core-java-collections/pom.xml
@@ -25,6 +25,11 @@
             <artifactId>jmh-generator-annprocess</artifactId>
             <version>${jmh-generator.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
     </dependencies>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-collections-3/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java b/core-java-modules/core-java-collections/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java
similarity index 95%
rename from core-java-modules/core-java-collections-3/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java
rename to core-java-modules/core-java-collections/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java
index f7be99abdc..1e6efb7840 100644
--- a/core-java-modules/core-java-collections-3/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java
+++ b/core-java-modules/core-java-collections/src/main/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToList.java
@@ -1,13 +1,15 @@
-package com.baeldung.collections.iterators;
+package com.baeldung.collections.convertarrayprimitives;
 
-import java.util.List;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
-import com.google.common.primitives.Ints;
+
 import org.apache.commons.lang3.ArrayUtils;
 
+import com.google.common.primitives.Ints;
+
 public class ConvertPrimitivesArrayToList {
 
     public static void failConvert() {
diff --git a/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java b/core-java-modules/core-java-collections/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java
similarity index 87%
rename from core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java
rename to core-java-modules/core-java-collections/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java
index b773baf7d8..f9f5f8ea91 100644
--- a/core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java
+++ b/core-java-modules/core-java-collections/src/test/java/com/baeldung/collections/convertarrayprimitives/ConvertPrimitivesArrayToListUnitTest.java
@@ -1,14 +1,11 @@
-package com.baeldung.collections.iterators;
-
-import java.util.List;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.stream.Collectors;
-import com.google.common.primitives.Ints;
-import org.junit.Test;
+package com.baeldung.collections.convertarrayprimitives;
 
 import static org.junit.Assert.assertEquals;
 
+import java.util.Arrays;
+
+import org.junit.Test;
+
 public class ConvertPrimitivesArrayToListUnitTest {
 
     @Test
diff --git a/core-java-modules/core-java-concurrency-advanced/pom.xml b/core-java-modules/core-java-concurrency-advanced/pom.xml
index a026bdb2cd..b50a66cefc 100644
--- a/core-java-modules/core-java-concurrency-advanced/pom.xml
+++ b/core-java-modules/core-java-concurrency-advanced/pom.xml
@@ -56,7 +56,6 @@
     <properties>
         <guava.version>21.0</guava.version>
         <commons-math3.version>3.6.1</commons-math3.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <collections-generic.version>4.01</collections-generic.version>
         <avaitility.version>1.7.0</avaitility.version>
     </properties>
diff --git a/core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/illegalmonitorstate/IllegalMonitorStateExceptionUnitTest.java b/core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/illegalmonitorstate/IllegalMonitorStateExceptionUnitTest.java
index bef90e671f..857ab02c13 100644
--- a/core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/illegalmonitorstate/IllegalMonitorStateExceptionUnitTest.java
+++ b/core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/illegalmonitorstate/IllegalMonitorStateExceptionUnitTest.java
@@ -1,11 +1,12 @@
 package com.baeldung.exceptions.illegalmonitorstate;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import org.junit.jupiter.api.Test;
 
-import java.time.Duration;
-
-import static org.junit.jupiter.api.Assertions.*;
-
 public class IllegalMonitorStateExceptionUnitTest {
 
     @Test
@@ -20,11 +21,11 @@ public class IllegalMonitorStateExceptionUnitTest {
         Thread senderThread = new Thread(sender, "sender-thread");
         senderThread.start();
 
-        senderThread.join(1000);
-        receiverThread.join(1000);
+        // we need to wait for the sender and receiver threads to finish
+        senderThread.join(10_000);
+        receiverThread.join(10_000);
 
-        // we need to wait for enough time so that sender has had a chance to send the data
-        assertTimeout(Duration.ofSeconds(10), () -> assertEquals("test", receiver.getMessage()));
+        assertEquals("test", receiver.getMessage());
         assertFalse(sender.hasIllegalMonitorStateExceptionOccurred());
         assertFalse(receiver.hasIllegalMonitorStateExceptionOccurred());
     }
diff --git a/core-java-modules/core-java-lang-oop-methods/pom.xml b/core-java-modules/core-java-lang-oop-methods/pom.xml
index e57b51b7bd..e41c56fc6f 100644
--- a/core-java-modules/core-java-lang-oop-methods/pom.xml
+++ b/core-java-modules/core-java-lang-oop-methods/pom.xml
@@ -2,6 +2,7 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
     <modelVersion>4.0.0</modelVersion>
     <artifactId>core-java-lang-oop-methods</artifactId>
     <name>core-java-lang-oop-methods</name>
@@ -33,7 +34,9 @@
     </dependencies>
 
     <properties>
-        <lombok.version>1.18.12</lombok.version>
+        <lombok.version>1.18.22</lombok.version>
+        <commons-lang.version>2.6</commons-lang.version>
+        <assertj-core.version>3.10.0</assertj-core.version>
         <equalsverifier.version>3.0.3</equalsverifier.version>
     </properties>
 
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/StringUtils.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/StringUtils.java
new file mode 100644
index 0000000000..1e94281d21
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/StringUtils.java
@@ -0,0 +1,17 @@
+package com.baeldung.utilities;
+
+public final class StringUtils {
+
+    private StringUtils() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+
+    public static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    public static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsEnum.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsEnum.java
new file mode 100644
index 0000000000..2fa96874c0
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsEnum.java
@@ -0,0 +1,13 @@
+package com.baeldung.utilities.alternatives;
+
+public enum StringUtilsEnum {;
+
+    public static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    public static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsInterface.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsInterface.java
new file mode 100644
index 0000000000..b6afdfff5d
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/alternatives/StringUtilsInterface.java
@@ -0,0 +1,13 @@
+package com.baeldung.utilities.alternatives;
+
+public interface StringUtilsInterface {
+
+    static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructor.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructor.java
new file mode 100644
index 0000000000..38e60e0216
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructor.java
@@ -0,0 +1,17 @@
+package com.baeldung.utilities.lombok;
+
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor(access= AccessLevel.PRIVATE)
+public final class StringUtilsWithNoArgsConstructor {
+
+    public static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    public static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClass.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClass.java
new file mode 100644
index 0000000000..56718f8ce4
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClass.java
@@ -0,0 +1,16 @@
+package com.baeldung.utilities.lombok;
+
+import lombok.experimental.UtilityClass;
+
+@UtilityClass
+public class StringUtilsWithUtilityClass {
+
+    public static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    public static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/warning/StringUtilsSuppressWarning.java b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/warning/StringUtilsSuppressWarning.java
new file mode 100644
index 0000000000..d8354f993d
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/utilities/warning/StringUtilsSuppressWarning.java
@@ -0,0 +1,14 @@
+package com.baeldung.utilities.warning;
+
+@SuppressWarnings("java:S1118")
+public final class StringUtilsSuppressWarning {
+
+    public static boolean isEmpty(String source) {
+        return source == null || source.length() == 0;
+    }
+
+    public static String wrap(String source, String wrapWith) {
+        return isEmpty(source) ? source : wrapWith + source + wrapWith;
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/StringUtilsUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/StringUtilsUnitTest.java
new file mode 100644
index 0000000000..ca8b270d8d
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/StringUtilsUnitTest.java
@@ -0,0 +1,28 @@
+package com.baeldung.utilities;
+
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.*;
+
+class StringUtilsUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtils.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtils.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtils.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtils.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsEnumUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsEnumUnitTest.java
new file mode 100644
index 0000000000..4d948c44ae
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsEnumUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.utilities.alternatives;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringUtilsEnumUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtilsEnum.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtilsEnum.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtilsEnum.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtilsEnum.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsInterfaceUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsInterfaceUnitTest.java
new file mode 100644
index 0000000000..600f6c2156
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/alternatives/StringUtilsInterfaceUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.utilities.alternatives;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringUtilsInterfaceUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtilsInterface.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtilsInterface.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtilsInterface.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtilsInterface.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructorUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructorUnitTest.java
new file mode 100644
index 0000000000..b110c31080
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithNoArgsConstructorUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.utilities.lombok;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringUtilsWithNoArgsConstructorUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtilsWithNoArgsConstructor.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtilsWithNoArgsConstructor.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtilsWithNoArgsConstructor.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtilsWithNoArgsConstructor.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClassUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClassUnitTest.java
new file mode 100644
index 0000000000..c2f5003ada
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/lombok/StringUtilsWithUtilityClassUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.utilities.lombok;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringUtilsWithUtilityClassUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtilsWithUtilityClass.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtilsWithUtilityClass.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtilsWithUtilityClass.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtilsWithUtilityClass.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/warning/StringUtilsStringUtilsSuppressWarningUnitTest.java b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/warning/StringUtilsStringUtilsSuppressWarningUnitTest.java
new file mode 100644
index 0000000000..646da08cc4
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-methods/src/test/java/com/baeldung/utilities/warning/StringUtilsStringUtilsSuppressWarningUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.utilities.warning;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringUtilsStringUtilsSuppressWarningUnitTest {
+
+    @Test
+    void givenAnEmptyString_whenCallingIsEmpty_thenResultIsTrue() {
+        assertThat(StringUtilsSuppressWarning.isEmpty("")).isTrue();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingIsEmpty_thenResultIsFalse() {
+        assertThat(StringUtilsSuppressWarning.isEmpty("asd")).isFalse();
+    }
+
+    @Test
+    void givenAnEmptyString_whenCallingWrap_thenResultIsAnEmptyString() {
+        assertThat(StringUtilsSuppressWarning.wrap("", "wrapper")).isEmpty();
+    }
+
+    @Test
+    void givenNonEmptyString_whenCallingWrap_thenResultIsWrappedString() {
+        assertThat(StringUtilsSuppressWarning.wrap("asd", "wrapper")).isEqualTo("wrapperasdwrapper");
+    }
+
+}
diff --git a/core-java-modules/core-java-networking-3/README.md b/core-java-modules/core-java-networking-3/README.md
index 0dc9ad9f70..82e75820ba 100644
--- a/core-java-modules/core-java-networking-3/README.md
+++ b/core-java-modules/core-java-networking-3/README.md
@@ -9,4 +9,5 @@ This module contains articles about networking in Java
 - [Connection Timeout vs. Read Timeout for Java Sockets](https://www.baeldung.com/java-socket-connection-read-timeout)
 - [Find Whether an IP Address Is in the Specified Range or Not in Java](https://www.baeldung.com/java-check-ip-address-range)
 - [Find the IP Address of a Client Connected to a Server](https://www.baeldung.com/java-client-get-ip-address)
+- [Unix Domain Socket in Java 16](https://www.baeldung.com/java-unix-domain-socket)
 - [[<-- Prev]](/core-java-modules/core-java-networking-2)
diff --git a/core-java-modules/core-java-networking-3/src/test/java/com/baeldung/socket/FindFreePortUnitTest.java b/core-java-modules/core-java-networking-3/src/test/java/com/baeldung/socket/FindFreePortUnitTest.java
index 95530ef292..4dfc114438 100644
--- a/core-java-modules/core-java-networking-3/src/test/java/com/baeldung/socket/FindFreePortUnitTest.java
+++ b/core-java-modules/core-java-networking-3/src/test/java/com/baeldung/socket/FindFreePortUnitTest.java
@@ -4,36 +4,26 @@ import org.apache.catalina.LifecycleException;
 import org.apache.catalina.startup.Tomcat;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
-import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 import org.springframework.util.SocketUtils;
 
 import java.io.IOException;
 import java.net.ServerSocket;
 
-import static org.assertj.core.api.Assertions.*;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
 
 public class FindFreePortUnitTest {
 
-    private static int FREE_PORT_NUMBER;
-    private static int[] FREE_PORT_RANGE;
-
-    @BeforeAll
-    public static void getExplicitFreePortNumberAndRange() {
-        try (ServerSocket serverSocket = new ServerSocket(0)) {
-            FREE_PORT_NUMBER = serverSocket.getLocalPort();
-            FREE_PORT_RANGE = new int[] {FREE_PORT_NUMBER, FREE_PORT_NUMBER + 1, FREE_PORT_NUMBER + 2};
-        } catch (IOException e) {
-            fail("No free port is available");
-        }
-    }
+    private static final int DEFAULT_RANDOM_PORT = 34307;
 
     @Test
     public void givenExplicitFreePort_whenCreatingServerSocket_thenThatPortIsAssigned() {
-        try (ServerSocket serverSocket = new ServerSocket(FREE_PORT_NUMBER)) {
+        int freePort = getFreePort();
+
+        try (ServerSocket serverSocket = new ServerSocket(freePort)) {
             assertThat(serverSocket).isNotNull();
-            assertThat(serverSocket.getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+            assertThat(serverSocket.getLocalPort()).isEqualTo(freePort);
         } catch (IOException e) {
             fail("Port is not available");
         }
@@ -41,8 +31,10 @@ public class FindFreePortUnitTest {
 
     @Test
     public void givenExplicitOccupiedPort_whenCreatingServerSocket_thenExceptionIsThrown() {
-        try (ServerSocket serverSocket = new ServerSocket(FREE_PORT_NUMBER)) {
-            new ServerSocket(FREE_PORT_NUMBER);
+        int freePort = getFreePort();
+
+        try (ServerSocket serverSocket = new ServerSocket(freePort)) {
+            new ServerSocket(freePort);
             fail("Same port cannot be used twice");
         } catch (IOException e) {
             assertThat(e).hasMessageContaining("Address already in use");
@@ -51,7 +43,7 @@ public class FindFreePortUnitTest {
 
     @Test
     public void givenExplicitPortRange_whenCreatingServerSocket_thenOnePortIsAssigned() {
-        for (int port : FREE_PORT_RANGE) {
+        for (int port : getFreePorts()) {
             try (ServerSocket serverSocket = new ServerSocket(port)) {
                 assertThat(serverSocket).isNotNull();
                 assertThat(serverSocket.getLocalPort()).isEqualTo(port);
@@ -104,11 +96,12 @@ public class FindFreePortUnitTest {
     public void givenExplicitFreePort_whenCreatingJettyServer_thenThatPortIsAssigned() throws Exception {
         Server jettyServer = new Server();
         ServerConnector serverConnector = new ServerConnector(jettyServer);
-        serverConnector.setPort(FREE_PORT_NUMBER);
+        int freePort = getFreePort();
+        serverConnector.setPort(freePort);
         jettyServer.addConnector(serverConnector);
         try {
             jettyServer.start();
-            assertThat(serverConnector.getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+            assertThat(serverConnector.getLocalPort()).isEqualTo(freePort);
         } catch (Exception e) {
             fail("Failed to start Jetty server");
         } finally {
@@ -135,10 +128,11 @@ public class FindFreePortUnitTest {
     @Test
     public void givenExplicitFreePort_whenCreatingTomcatServer_thenThatPortIsAssigned() throws Exception {
         Tomcat tomcatServer = new Tomcat();
-        tomcatServer.setPort(FREE_PORT_NUMBER);
+        int freePort = getFreePort();
+        tomcatServer.setPort(freePort);
         try {
             tomcatServer.start();
-            assertThat(tomcatServer.getConnector().getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+            assertThat(tomcatServer.getConnector().getLocalPort()).isEqualTo(freePort);
         } catch (LifecycleException e) {
             fail("Failed to start Tomcat server");
         } finally {
@@ -147,4 +141,16 @@ public class FindFreePortUnitTest {
         }
     }
 
+    private int[] getFreePorts() {
+        int freePort = getFreePort();
+        return new int[]{freePort - 1, freePort, freePort + 1};
+    }
+
+    private int getFreePort() {
+        try(ServerSocket serverSocket = new ServerSocket(0)){
+            return serverSocket.getLocalPort();
+        } catch (IOException ex){
+            return DEFAULT_RANDOM_PORT;
+        }
+    }
 }
diff --git a/core-java-modules/core-java-os/pom.xml b/core-java-modules/core-java-os/pom.xml
index d2bf842897..54b86522f4 100644
--- a/core-java-modules/core-java-os/pom.xml
+++ b/core-java-modules/core-java-os/pom.xml
@@ -75,7 +75,6 @@
     </build>
 
     <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <collections-generic.version>4.01</collections-generic.version>
         <asspectj.version>1.8.9</asspectj.version>
         <maven.compiler.source>1.9</maven.compiler.source>
diff --git a/core-java-modules/core-java-perf/src/main/java/com/baeldung/jmx/JMXConfiguration.java b/core-java-modules/core-java-perf/src/main/java/com/baeldung/jmx/JMXConfiguration.java
new file mode 100644
index 0000000000..e60ea253ed
--- /dev/null
+++ b/core-java-modules/core-java-perf/src/main/java/com/baeldung/jmx/JMXConfiguration.java
@@ -0,0 +1,10 @@
+package com.baeldung.jmx;
+
+public class JMXConfiguration {
+
+    public static void main(String[] args) {
+        while (true) {
+            // to ensure application does not terminate
+        }
+    }
+}
\ No newline at end of file
diff --git a/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/matcher/MatcherUnitTest.java b/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/matcher/MatcherUnitTest.java
index 304b9f2f1d..7ec4a1ae58 100644
--- a/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/matcher/MatcherUnitTest.java
+++ b/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/matcher/MatcherUnitTest.java
@@ -11,6 +11,9 @@ import org.junit.jupiter.api.Test;
 
 public class MatcherUnitTest {
 
+    private static final String STRING_INPUT = "test+";
+    private static final String REGEX = "\\+";
+
     @Test
     public void whenFindFourDigitWorks_thenCorrect() {
         Pattern stringPattern = Pattern.compile("\\d\\d\\d\\d");
@@ -60,4 +63,16 @@ public class MatcherUnitTest {
         assertTrue(m.matches());// matches will always return the same return
     }
 
+    @Test
+    public void whenUsingMatcher_thenReturnTrue() {
+        Pattern pattern = Pattern.compile(REGEX);
+        Matcher matcher = pattern.matcher(STRING_INPUT);
+        assertTrue(matcher.find());
+    }
+
+    @Test
+    public void whenUsingMatches_thenReturnFalse() {
+        assertFalse(Pattern.matches(REGEX, STRING_INPUT));
+    }
+
 }
diff --git a/core-java-modules/core-java-string-algorithms-2/README.md b/core-java-modules/core-java-string-algorithms-2/README.md
index aa71e5f59e..dbfbb3ef3c 100644
--- a/core-java-modules/core-java-string-algorithms-2/README.md
+++ b/core-java-modules/core-java-string-algorithms-2/README.md
@@ -13,5 +13,4 @@ This module contains articles about string-related algorithms.
 - [Remove Leading and Trailing Characters from a String](https://www.baeldung.com/java-remove-trailing-characters)
 - [Counting Words in a String with Java](https://www.baeldung.com/java-word-counting)
 - [Finding the Difference Between Two Strings in Java](https://www.baeldung.com/java-difference-between-two-strings)
-- [Check if the First Letter of a String is Uppercase](https://www.baeldung.com/java-check-first-letter-uppercase)
 - More articles: [[<-- prev]](../core-java-string-algorithms)
diff --git a/core-java-modules/core-java-string-algorithms-3/README.md b/core-java-modules/core-java-string-algorithms-3/README.md
index 8d515b9aea..e6dbf3a489 100644
--- a/core-java-modules/core-java-string-algorithms-3/README.md
+++ b/core-java-modules/core-java-string-algorithms-3/README.md
@@ -6,3 +6,4 @@ This module contains articles about string-related algorithms.
 
 - [Check if Two Strings are Anagrams in Java](https://www.baeldung.com/java-strings-anagrams)
 - [Email Validation in Java](https://www.baeldung.com/java-email-validation-regex)
+- [Check if the First Letter of a String is Uppercase](https://www.baeldung.com/java-check-first-letter-uppercase)
diff --git a/core-java-modules/core-java-string-algorithms-3/pom.xml b/core-java-modules/core-java-string-algorithms-3/pom.xml
index 6700e9ba95..ccb9457a11 100644
--- a/core-java-modules/core-java-string-algorithms-3/pom.xml
+++ b/core-java-modules/core-java-string-algorithms-3/pom.xml
@@ -49,8 +49,8 @@
     </build>
 
     <properties>
-        <guava.version>28.1-jre</guava.version>
+        <guava.version>31.0.1-jre</guava.version>
         <validator.version>1.7</validator.version>
     </properties>
 
-</project>
\ No newline at end of file
+</project>
diff --git a/core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java b/core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercaseUnitTest.java
similarity index 80%
rename from core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
rename to core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercaseUnitTest.java
index 0d9d3b6431..524f7ca839 100644
--- a/core-java-modules/core-java-string-algorithms-2/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercase.java
+++ b/core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/isuppercase/StringFirstCharacterUppercaseUnitTest.java
@@ -1,15 +1,12 @@
 package com.baeldung.isuppercase;
 
-import com.google.common.base.Ascii;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestInstance;
-
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.matchesPattern;
+import com.google.common.base.Ascii;
 
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
-public class StringFirstCharacterUppercase {
+public class StringFirstCharacterUppercaseUnitTest {
 
     @Test
     public void givenString_whenCheckingWithCharacterIsUpperCase_thenStringCapitalized() {
@@ -21,7 +18,8 @@ public class StringFirstCharacterUppercase {
     public void givenString_whenCheckingWithRegex_thenStringCapitalized() {
         String example = "Katie";
         String regEx = "[A-Z]\\w*";
-        assertThat(example, matchesPattern(regEx));
+
+        Assertions.assertTrue(example.matches(regEx));
     }
 
     @Test
diff --git a/core-java-modules/core-java-string-conversions-2/README.md b/core-java-modules/core-java-string-conversions-2/README.md
index 46eb783a27..22f4cd89a1 100644
--- a/core-java-modules/core-java-string-conversions-2/README.md
+++ b/core-java-modules/core-java-string-conversions-2/README.md
@@ -9,4 +9,5 @@ This module contains articles about string conversions from/to another type.
 - [Converting String to BigDecimal in Java](https://www.baeldung.com/java-string-to-bigdecimal)
 - [Converting String to BigInteger in Java](https://www.baeldung.com/java-string-to-biginteger)
 - [Convert a String to Camel Case](https://www.baeldung.com/java-string-to-camel-case)
+- [Convert a ByteBuffer to String]
 - More articles: [[<-- prev]](/core-java-string-conversions)
diff --git a/core-java-modules/core-java-string-conversions-2/src/test/java/com/baeldung/bytebuffertostring/ByteArrayToStringUnitTest.java b/core-java-modules/core-java-string-conversions-2/src/test/java/com/baeldung/bytebuffertostring/ByteArrayToStringUnitTest.java
new file mode 100644
index 0000000000..c498921d9a
--- /dev/null
+++ b/core-java-modules/core-java-string-conversions-2/src/test/java/com/baeldung/bytebuffertostring/ByteArrayToStringUnitTest.java
@@ -0,0 +1,44 @@
+package com.baeldung.bytebuffertostring;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Test;
+
+public class ByteArrayToStringUnitTest {
+    private static Charset charset = StandardCharsets.UTF_8;
+    private static final String content = "baeldung";
+
+    @Test
+    public void convertUsingNewStringFromBufferArray_thenOK() {
+        // Allocate a ByteBuffer
+        ByteBuffer byteBuffer = ByteBuffer.wrap(content.getBytes());
+        if (byteBuffer.hasArray()) {
+            String newContent = new String(byteBuffer.array(), charset);
+            assertEquals(content, newContent);
+        }
+    }
+
+    @Test
+    public void convertUsingNewStringFromByteBufferGetBytes_thenOK() {
+        // Allocate a ByteBuffer
+        ByteBuffer byteBuffer = ByteBuffer.wrap(content.getBytes());
+        byte[] bytes = new byte[byteBuffer.remaining()];
+        byteBuffer.get(bytes);
+        String newContent = new String(bytes, charset);
+        assertEquals(content, newContent);
+    }
+
+    @Test
+    public void convertUsingCharsetDecode_thenOK() {
+        // Allocate a ByteBuffer
+        ByteBuffer byteBuffer = ByteBuffer.wrap(content.getBytes());
+        String newContent = charset.decode(byteBuffer)
+            .toString();
+        assertEquals(content, newContent);
+    }
+
+}
diff --git a/core-java-modules/core-java-string-operations-2/src/test/java/com/baeldung/hexToAscii/README.md b/core-java-modules/core-java-string-operations-2/src/test/java/com/baeldung/hexToAscii/README.md
deleted file mode 100644
index c6d5826333..0000000000
--- a/core-java-modules/core-java-string-operations-2/src/test/java/com/baeldung/hexToAscii/README.md
+++ /dev/null
@@ -1,2 +0,0 @@
-### Relevant Articles:
-- [Convert Hex to ASCII in Java](http://www.baeldung.com/java-convert-hex-to-ascii)
diff --git a/core-java-modules/core-java-string-operations-4/README.md b/core-java-modules/core-java-string-operations-4/README.md
index be4c9ae05f..83bfeb4d05 100644
--- a/core-java-modules/core-java-string-operations-4/README.md
+++ b/core-java-modules/core-java-string-operations-4/README.md
@@ -2,4 +2,5 @@
 
 - [Ignoring Commas in Quotes When Splitting a Comma-separated String](https://www.baeldung.com/java-split-string-commas)
 - [Compare Strings While Ignoring Whitespace in Java](https://www.baeldung.com/java-compare-string-whitespace)
+- [Concatenating Null Strings in Java](https://www.baeldung.com/java-concat-null-string)
 
diff --git a/core-java-modules/core-java-string-operations-4/src/main/java/com/baeldung/concatenation/ConcatenatingNull.java b/core-java-modules/core-java-string-operations-4/src/main/java/com/baeldung/concatenation/ConcatenatingNull.java
new file mode 100644
index 0000000000..250a0d6b25
--- /dev/null
+++ b/core-java-modules/core-java-string-operations-4/src/main/java/com/baeldung/concatenation/ConcatenatingNull.java
@@ -0,0 +1,86 @@
+package com.baeldung.concatenation;
+
+import java.util.StringJoiner;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class ConcatenatingNull {
+
+    public static void main(String[] args) {
+        String[] values = { "Java ", null, "", "is ", "great!" };
+
+        concatenateUsingPlusOperator(values);
+        concatenateUsingHelperMethod(values);
+        concatenateUsingStringBuilder(values);
+        concatenateUsingJoin(values);
+        concatenateUsingStringJoiner(values);
+        concatenateUsingCollectorsJoining(values);
+        concatenateUsingStringConcat(values);
+    }
+
+    public static String concatenateUsingStringConcat(String[] values) {
+        String result = "";
+
+        for (String value : values) {
+            result = result.concat(getNonNullString(value));
+        }
+
+        return result;
+    }
+
+    public static String concatenateUsingCollectorsJoining(String[] values) {
+        String result = Stream.of(values).filter(value -> null != value).collect(Collectors.joining(""));
+
+        return result;
+    }
+
+    public static String concatenateUsingStringJoiner(String[] values) {
+        StringJoiner result = new StringJoiner("");
+
+        for (String value : values) {
+            result = result.add(getNonNullString(value));
+        }
+
+        return result.toString();
+    }
+
+    public static String concatenateUsingJoin(String[] values) {
+        String result = String.join("", values);
+
+        return result;
+    }
+
+    public static String concatenateUsingStringBuilder(String[] values) {
+        StringBuilder result = new StringBuilder();
+
+        for (String value : values) {
+            result = result.append(getNonNullString(value));
+        }
+
+        return result.toString();
+    }
+
+    public static String concatenateUsingHelperMethod(String[] values) {
+        String result = "";
+
+        for (String value : values) {
+            result = result + getNonNullString(value);
+        }
+
+        return result;
+    }
+
+    public static String concatenateUsingPlusOperator(String[] values) {
+        String result = "";
+
+        for (String value : values) {
+            result = result + (value == null ? "" : value);
+        }
+
+        return result;
+    }
+
+    private static String getNonNullString(String value) {
+        return value == null ? "" : value;
+    }
+}
diff --git a/core-java-modules/core-java-string-operations-4/src/test/java/com/baeldung/concatenation/ConcatenatingNullUnitTest.java b/core-java-modules/core-java-string-operations-4/src/test/java/com/baeldung/concatenation/ConcatenatingNullUnitTest.java
new file mode 100644
index 0000000000..20e5f6ad7d
--- /dev/null
+++ b/core-java-modules/core-java-string-operations-4/src/test/java/com/baeldung/concatenation/ConcatenatingNullUnitTest.java
@@ -0,0 +1,59 @@
+package com.baeldung.concatenation;
+
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingCollectorsJoining;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingHelperMethod;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingJoin;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingPlusOperator;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingStringBuilder;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingStringConcat;
+import static com.baeldung.concatenation.ConcatenatingNull.concatenateUsingStringJoiner;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class ConcatenatingNullUnitTest {
+
+    String[] values = { "Java ", null, "", "is ", "great!" };
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingPlus_thenNullIsIgnored() {
+        String result = concatenateUsingPlusOperator(values);
+        assertEquals("Java is great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingHelperMethod_thenNullIsIgnored() {
+        String result = concatenateUsingHelperMethod(values);
+        assertEquals("Java is great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingStringBuilder_thenNullIsIgnored() {
+        String result = concatenateUsingStringBuilder(values);
+        assertEquals("Java is great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingJoin_thenNullIsNotIgnored() {
+        String result = concatenateUsingJoin(values);
+        assertEquals("Java nullis great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingStringJoiner_thenNullIsIgnored() {
+        String result = concatenateUsingStringJoiner(values);
+        assertEquals("Java is great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingCollectorsJoining_thenNullIsIgnored() {
+        String result = concatenateUsingCollectorsJoining(values);
+        assertEquals("Java is great!", result);
+    }
+
+    @Test
+    public void givenStringElementsWithNull_whenConcatenatedUsingStringConcat_thenNullIsIgnored() {
+        String result = concatenateUsingStringConcat(values);
+        assertEquals("Java is great!", result);
+    }
+}
diff --git a/core-java-modules/core-java-time-measurements/pom.xml b/core-java-modules/core-java-time-measurements/pom.xml
index e2924b5278..28959d0938 100644
--- a/core-java-modules/core-java-time-measurements/pom.xml
+++ b/core-java-modules/core-java-time-measurements/pom.xml
@@ -38,15 +38,15 @@
             <version>${asspectj.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-module-junit4</artifactId>
-            <version>${powermock.version}</version>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-inline</artifactId>
+            <version>${mockito-inline.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-api-mockito2</artifactId>
-            <version>${powermock.version}</version>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${mockito-inline.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -82,10 +82,10 @@
     <properties>
         <commons-math3.version>3.6.1</commons-math3.version>
         <joda.version>2.10</joda.version>
-        <lombok.version>1.18.12</lombok.version>
+        <lombok.version>1.18.22</lombok.version>
         <asspectj.version>1.8.9</asspectj.version>
-        <powermock.version>2.0.7</powermock.version>
         <jmockit.version>1.44</jmockit.version>
+        <mockito-inline.version>4.0.0</mockito-inline.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/InstantUnitTest.java b/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/InstantUnitTest.java
index 608199197a..ba1821b1ce 100644
--- a/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/InstantUnitTest.java
+++ b/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/InstantUnitTest.java
@@ -1,20 +1,15 @@
 package com.baeldung.time;
 
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.powermock.core.classloader.annotations.PrepareForTest;
-import org.powermock.modules.junit4.PowerMockRunner;
+import org.mockito.MockedStatic;
 
 import java.time.Clock;
 import java.time.Instant;
 import java.time.ZoneId;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.powermock.api.mockito.PowerMockito.mockStatic;
-import static org.powermock.api.mockito.PowerMockito.when;
+import static org.mockito.Mockito.mockStatic;
 
-@RunWith(PowerMockRunner.class)
-@PrepareForTest({ Instant.class })
 public class InstantUnitTest {
 
     @Test
@@ -22,12 +17,12 @@ public class InstantUnitTest {
         String instantExpected = "2014-12-22T10:15:30Z";
         Clock clock = Clock.fixed(Instant.parse(instantExpected), ZoneId.of("UTC"));
         Instant instant = Instant.now(clock);
-        mockStatic(Instant.class);
-        when(Instant.now()).thenReturn(instant);
 
-        Instant now = Instant.now();
-
-        assertThat(now.toString()).isEqualTo(instantExpected);
+        try (MockedStatic<Instant> mockedStatic = mockStatic(Instant.class)) {
+            mockedStatic.when(Instant::now).thenReturn(instant);
+            Instant now = Instant.now();
+            assertThat(now.toString()).isEqualTo(instantExpected);
+        }
     }
 
     @Test
diff --git a/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/LocalDateTimeUnitTest.java b/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/LocalDateTimeUnitTest.java
index 52dc9ba1c6..e4401d67b7 100644
--- a/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/LocalDateTimeUnitTest.java
+++ b/core-java-modules/core-java-time-measurements/src/test/java/com/baeldung/time/LocalDateTimeUnitTest.java
@@ -1,9 +1,6 @@
 package com.baeldung.time;
 
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.powermock.core.classloader.annotations.PrepareForTest;
-import org.powermock.modules.junit4.PowerMockRunner;
 
 import java.time.Clock;
 import java.time.Instant;
@@ -11,11 +8,7 @@ import java.time.LocalDateTime;
 import java.time.ZoneId;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.mockito.Mockito.when;
-import static org.powermock.api.mockito.PowerMockito.mockStatic;
 
-@RunWith(PowerMockRunner.class)
-@PrepareForTest({ LocalDateTime.class })
 public class LocalDateTimeUnitTest {
 
     @Test
diff --git a/gson/pom.xml b/gson/pom.xml
index a928d87b61..082e53baf0 100644
--- a/gson/pom.xml
+++ b/gson/pom.xml
@@ -61,10 +61,7 @@
     </build>
 
     <properties>
-        <!-- marshalling -->
         <gson.version>2.8.0</gson.version>
-        <!-- util -->
-        <commons-collections4.version>4.1</commons-collections4.version>
         <joda-time.version>2.9.6</joda-time.version>
     </properties>
 
diff --git a/guava-modules/guava-collections-list/pom.xml b/guava-modules/guava-collections-list/pom.xml
index 1b989e79b0..6863b4011c 100644
--- a/guava-modules/guava-collections-list/pom.xml
+++ b/guava-modules/guava-collections-list/pom.xml
@@ -45,9 +45,6 @@
     </build>
 
     <properties>
-        <!-- util -->
-        <commons-collections4.version>4.1</commons-collections4.version>
-        <!-- testing -->
         <java-hamcrest.version>2.0.0.0</java-hamcrest.version>
     </properties>
 
diff --git a/guava-modules/guava-collections/pom.xml b/guava-modules/guava-collections/pom.xml
index 7929283616..9283107023 100644
--- a/guava-modules/guava-collections/pom.xml
+++ b/guava-modules/guava-collections/pom.xml
@@ -50,10 +50,7 @@
     </build>
 
     <properties>
-        <!-- util -->
-        <commons-collections4.version>4.1</commons-collections4.version>
         <jool.version>0.9.12</jool.version>
-        <!-- testing -->
         <java-hamcrest.version>2.0.0.0</java-hamcrest.version>
     </properties>
 
diff --git a/jackson-modules/jackson-conversions-2/README.md b/jackson-modules/jackson-conversions-2/README.md
index bddbb60bd7..fa3568652a 100644
--- a/jackson-modules/jackson-conversions-2/README.md
+++ b/jackson-modules/jackson-conversions-2/README.md
@@ -11,4 +11,5 @@ This module contains articles about Jackson conversions.
 - [Jackson Streaming API](https://www.baeldung.com/jackson-streaming-api)
 - [Jackson: java.util.LinkedHashMap cannot be cast to X](https://www.baeldung.com/jackson-linkedhashmap-cannot-be-cast)
 - [Deserialize Snake Case to Camel Case With Jackson](https://www.baeldung.com/jackson-deserialize-snake-to-camel-case)
+- [Serialize and Deserialize Booleans as Integers With Jackson](https://www.baeldung.com/jackson-booleans-as-integers)
 - More articles: [[<-- prev]](../jackson-conversions)
diff --git a/java-collections-conversions/pom.xml b/java-collections-conversions/pom.xml
index ae800b21c1..7f5ba38e3e 100644
--- a/java-collections-conversions/pom.xml
+++ b/java-collections-conversions/pom.xml
@@ -38,8 +38,4 @@
         </resources>
     </build>
 
-    <properties>
-        <commons-collections4.version>4.4</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/java-collections-maps-3/pom.xml b/java-collections-maps-3/pom.xml
index 6f724ab5ef..81466b17ba 100644
--- a/java-collections-maps-3/pom.xml
+++ b/java-collections-maps-3/pom.xml
@@ -30,7 +30,6 @@
     </dependencies>
 
     <properties>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <spring.version>5.2.5.RELEASE</spring.version>
     </properties>
 
diff --git a/json-2/README.md b/json-2/README.md
index aebc42c472..ed5a79dd3d 100644
--- a/json-2/README.md
+++ b/json-2/README.md
@@ -8,3 +8,5 @@ This module contains articles about JSON.
 - [Introduction to Moshi Json](https://www.baeldung.com/java-json-moshi)
 - [Hypermedia Serialization With JSON-LD](https://www.baeldung.com/json-linked-data)
 - [Generate a Java Class From JSON](https://www.baeldung.com/java-generate-class-from-json)
+- [A Guide to FastJson](https://www.baeldung.com/fastjson)
+- More Articles: [[<-- prev]](/json)
diff --git a/json-2/pom.xml b/json-2/pom.xml
index 591b7c0883..751199d394 100644
--- a/json-2/pom.xml
+++ b/json-2/pom.xml
@@ -14,6 +14,11 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+            <version>${fastjson.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.jsonschema2pojo</groupId>
             <artifactId>jsonschema2pojo-core</artifactId>
@@ -142,6 +147,7 @@
     <properties>
         <jsoniter.version>0.9.23</jsoniter.version>
         <moshi.version>1.9.2</moshi.version>
+        <fastjson.version>1.2.21</fastjson.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/json/src/test/java/fast_json/FastJsonUnitTest.java b/json-2/src/test/java/com/baeldung/fastjson/FastJsonUnitTest.java
similarity index 99%
rename from json/src/test/java/fast_json/FastJsonUnitTest.java
rename to json-2/src/test/java/com/baeldung/fastjson/FastJsonUnitTest.java
index 6fcf1e398a..eec7a1c95f 100644
--- a/json/src/test/java/fast_json/FastJsonUnitTest.java
+++ b/json-2/src/test/java/com/baeldung/fastjson/FastJsonUnitTest.java
@@ -1,4 +1,4 @@
-package fast_json;
+package com.baeldung.fastjson;
 
 import com.alibaba.fastjson.JSON;
 import com.alibaba.fastjson.JSONArray;
diff --git a/json/src/test/java/fast_json/Person.java b/json-2/src/test/java/com/baeldung/fastjson/Person.java
similarity index 97%
rename from json/src/test/java/fast_json/Person.java
rename to json-2/src/test/java/com/baeldung/fastjson/Person.java
index 3d772348a4..5e142131a3 100644
--- a/json/src/test/java/fast_json/Person.java
+++ b/json-2/src/test/java/com/baeldung/fastjson/Person.java
@@ -1,4 +1,4 @@
-package fast_json;
+package com.baeldung.fastjson;
 
 import com.alibaba.fastjson.annotation.JSONField;
 
diff --git a/json/README.md b/json/README.md
index 6ad4c8a29d..0a4782cd86 100644
--- a/json/README.md
+++ b/json/README.md
@@ -4,7 +4,6 @@ This module contains articles about JSON.
 
 ### Relevant Articles:
 - [Introduction to JSON Schema in Java](https://www.baeldung.com/introduction-to-json-schema-in-java)
-- [A Guide to FastJson](https://www.baeldung.com/fastjson)
 - [Introduction to JSONForms](https://www.baeldung.com/introduction-to-jsonforms)
 - [Introduction to JsonPath](https://www.baeldung.com/guide-to-jayway-jsonpath)
 - [Introduction to JSON-Java (org.json)](https://www.baeldung.com/java-org-json)
@@ -14,3 +13,4 @@ This module contains articles about JSON.
 - [Iterating Over an Instance of org.json.JSONObject](https://www.baeldung.com/jsonobject-iteration)
 - [Escape JSON String in Java](https://www.baeldung.com/java-json-escaping)
 - [Reducing JSON Data Size](https://www.baeldung.com/json-reduce-data-size)
+- More Articles: [[next -->]](/json-2)
diff --git a/json/pom.xml b/json/pom.xml
index 2919a3a4ee..0d83f523b8 100644
--- a/json/pom.xml
+++ b/json/pom.xml
@@ -26,11 +26,6 @@
                 </exclusion>
             </exclusions>
         </dependency>
-        <dependency>
-            <groupId>com.alibaba</groupId>
-            <artifactId>fastjson</artifactId>
-            <version>${fastjson.version}</version>
-        </dependency>
         <dependency>
             <groupId>org.json</groupId>
             <artifactId>json</artifactId>
@@ -72,9 +67,7 @@
 
     <properties>
         <everit.json.schema.version>1.4.1</everit.json.schema.version>
-        <fastjson.version>1.2.21</fastjson.version>
         <jsonb-api.version>1.0</jsonb-api.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <yasson.version>1.0.1</yasson.version>
         <json.version>20171018</json.version>
         <gson.version>2.8.5</gson.version>
diff --git a/libraries-6/pom.xml b/libraries-6/pom.xml
index accf5f3a9a..3b932f2bd2 100644
--- a/libraries-6/pom.xml
+++ b/libraries-6/pom.xml
@@ -146,7 +146,6 @@
         <renjin.version>3.5-beta72</renjin.version>
         <rcaller.version>3.0</rcaller.version>
         <rserve.version>1.8.1</rserve.version>
-        <commons-collections4.version>4.4</commons-collections4.version>
         <libphonenumber.version>8.12.9</libphonenumber.version>
         <org.modelmapper.version>2.4.4</org.modelmapper.version>
     </properties>
diff --git a/libraries-apache-commons-collections/pom.xml b/libraries-apache-commons-collections/pom.xml
index 2cb73babe6..c1a158b16e 100644
--- a/libraries-apache-commons-collections/pom.xml
+++ b/libraries-apache-commons-collections/pom.xml
@@ -16,7 +16,7 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-collections4</artifactId>
-            <version>${commons.collections.version}</version>
+            <version>${commons-collections4.version}</version>
         </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>
@@ -27,7 +27,6 @@
     </dependencies>
 
     <properties>
-        <commons.collections.version>4.1</commons.collections.version>
         <org.hamcrest.java-hamcrest.version>2.0.0.0</org.hamcrest.java-hamcrest.version>
     </properties>
 
diff --git a/logging-modules/logback/pom.xml b/logging-modules/logback/pom.xml
index 48bb37b881..b4ee42367f 100644
--- a/logging-modules/logback/pom.xml
+++ b/logging-modules/logback/pom.xml
@@ -74,4 +74,40 @@
         <javax.activation.version>1.1.1</javax.activation.version>
     </properties>
 
+    <profiles>
+        <profile>
+            <id>integration-lite-first</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>integration-lite-second</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
 </project>
\ No newline at end of file
diff --git a/persistence-modules/java-jpa-3/README.md b/persistence-modules/java-jpa-3/README.md
index 202c97a830..aa33644b17 100644
--- a/persistence-modules/java-jpa-3/README.md
+++ b/persistence-modules/java-jpa-3/README.md
@@ -13,5 +13,4 @@ This module contains articles about the Java Persistence API (JPA) in Java.
 - [Returning an Auto-Generated Id with JPA](https://www.baeldung.com/jpa-get-auto-generated-id)
 - [How to Return Multiple Entities In JPA Query](https://www.baeldung.com/jpa-return-multiple-entities)
 - [Defining Unique Constraints in JPA](https://www.baeldung.com/jpa-unique-constraints)
-- [How to Check Field Existence in MongoDB?](https://www.baeldung.com/mongodb-check-field-exists)
 - [Connecting to a Specific Schema in JDBC](https://www.baeldung.com/jdbc-connect-to-schema)
diff --git a/persistence-modules/java-mongodb/README.md b/persistence-modules/java-mongodb/README.md
index f632e7c662..34acd60c57 100644
--- a/persistence-modules/java-mongodb/README.md
+++ b/persistence-modules/java-mongodb/README.md
@@ -11,3 +11,4 @@ This module contains articles about MongoDB in Java.
 - [Introduction to Morphia – Java ODM for MongoDB](https://www.baeldung.com/mongodb-morphia)
 - [MongoDB Aggregations Using Java](https://www.baeldung.com/java-mongodb-aggregations)
 - [BSON to JSON Document Conversion in Java](https://www.baeldung.com/java-convert-bson-to-json)
+- [How to Check Field Existence in MongoDB?](https://www.baeldung.com/mongodb-check-field-exists)
diff --git a/persistence-modules/java-mongodb/src/test/java/com/baeldung/existence.field/FieldExistenceLiveTest.java b/persistence-modules/java-mongodb/src/test/java/com/baeldung/existence/field/FieldExistenceLiveTest.java
similarity index 100%
rename from persistence-modules/java-mongodb/src/test/java/com/baeldung/existence.field/FieldExistenceLiveTest.java
rename to persistence-modules/java-mongodb/src/test/java/com/baeldung/existence/field/FieldExistenceLiveTest.java
diff --git a/persistence-modules/spring-boot-persistence/README.md b/persistence-modules/spring-boot-persistence/README.md
index a9fe3905c2..88526cdb89 100644
--- a/persistence-modules/spring-boot-persistence/README.md
+++ b/persistence-modules/spring-boot-persistence/README.md
@@ -7,5 +7,4 @@
 - [Resolving “Failed to Configure a DataSource” Error](https://www.baeldung.com/spring-boot-failed-to-configure-data-source)
 - [Hibernate Field Naming with Spring Boot](https://www.baeldung.com/hibernate-field-naming-spring-boot)
 - [Spring Boot with Hibernate](https://www.baeldung.com/spring-boot-hibernate)
-- [A Guide to Spring AbstractRoutingDatasource](https://www.baeldung.com/spring-abstract-routing-data-source)
-- More articles: [[more -->]](../spring-boot-persistence-2)
\ No newline at end of file
+- More articles: [[more -->]](../spring-boot-persistence-2)
diff --git a/persistence-modules/spring-jpa/README.md b/persistence-modules/spring-jpa/README.md
index 202f5b0293..aa9e833260 100644
--- a/persistence-modules/spring-jpa/README.md
+++ b/persistence-modules/spring-jpa/README.md
@@ -5,7 +5,6 @@
 - [JPA Pagination](https://www.baeldung.com/jpa-pagination)
 - [Sorting with JPA](https://www.baeldung.com/jpa-sort)
 - [Self-Contained Testing Using an In-Memory Database](https://www.baeldung.com/spring-jpa-test-in-memory-database)
-- [Obtaining Auto-generated Keys in Spring JDBC](https://www.baeldung.com/spring-jdbc-autogenerated-keys)
 - [Spring Data Annotations](http://www.baeldung.com/spring-data-annotations)
 - [A Guide to Spring AbstractRoutingDatasource](https://www.baeldung.com/spring-abstract-routing-data-source)
 - More articles: [[next -->]](/spring-jpa-2)
diff --git a/pom.xml b/pom.xml
index 780393dfab..ad002650d7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1433,6 +1433,7 @@
         <jmh-core.version>1.33</jmh-core.version>
         <jmh-generator.version>1.33</jmh-generator.version>
         <maven-failsafe-plugin.version>2.21.0</maven-failsafe-plugin.version>
+        <commons-collections4.version>4.4</commons-collections4.version>
         <commons-io.version>2.11.0</commons-io.version>
         <commons-lang.version>2.6</commons-lang.version>
         <commons-lang3.version>3.12.0</commons-lang3.version>
diff --git a/quarkus-jandex/README.md b/quarkus-jandex/README.md
new file mode 100644
index 0000000000..cca5fa7714
--- /dev/null
+++ b/quarkus-jandex/README.md
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Quarkus Bean Discovery With Jandex Indexing](https://www.baeldung.com/quarkus-bean-discovery-index)
diff --git a/quarkus-vs-springboot/spring-project/pom.xml b/quarkus-vs-springboot/spring-project/pom.xml
index 128966c07e..989e30526f 100644
--- a/quarkus-vs-springboot/spring-project/pom.xml
+++ b/quarkus-vs-springboot/spring-project/pom.xml
@@ -10,7 +10,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.5.4</version>
+        <version>2.6.0</version>
         <relativePath />
     </parent>
 
@@ -96,6 +96,15 @@
                 <enabled>false</enabled>
             </snapshots>
         </repository>
+        <!-- This can be removed once a stable version of org.springframework.experimental:spring-aot-maven-plugin, compatible with latest JDK, is released. -->
+        <repository>
+            <id>spring-milestones</id>
+            <name>Spring Milestones</name>
+            <url>https://repo.spring.io/libs-milestone-local</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+        </repository>
     </repositories>
     <pluginRepositories>
         <pluginRepository>
@@ -106,6 +115,15 @@
                 <enabled>false</enabled>
             </snapshots>
         </pluginRepository>
+        <!-- This can be removed once a stable version of org.springframework.experimental:spring-aot-maven-plugin, compatible with latest JDK, is released. -->
+        <pluginRepository>
+            <id>spring-milestones</id>
+            <name>Spring Milestones</name>
+            <url>https://repo.spring.io/libs-milestone-local</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+        </pluginRepository>
     </pluginRepositories>
 
     <profiles>
@@ -166,7 +184,7 @@
     <properties>
         <java.version>11</java.version>
         <repackage.classifier />
-        <spring-native.version>0.10.3</spring-native.version>
+        <spring-native.version>0.11.0-RC1</spring-native.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/spring-5-reactive-2/pom.xml b/spring-5-reactive-2/pom.xml
index 0758365932..e48d42a863 100644
--- a/spring-5-reactive-2/pom.xml
+++ b/spring-5-reactive-2/pom.xml
@@ -75,9 +75,45 @@
         </plugins>
     </build>
 
+    <profiles>
+        <profile>
+            <id>integration-lite-first</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>integration-lite-second</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
     <properties>
         <reactor-spring.version>1.0.1.RELEASE</reactor-spring.version>
         <wiremock.version>2.24.0</wiremock.version>
     </properties>
-
 </project>
\ No newline at end of file
diff --git a/spring-5-reactive-client/pom.xml b/spring-5-reactive-client/pom.xml
index 136f31b49e..f665d5c9a6 100644
--- a/spring-5-reactive-client/pom.xml
+++ b/spring-5-reactive-client/pom.xml
@@ -148,14 +148,49 @@
         </plugins>
     </build>
 
+    <profiles>
+        <profile>
+            <id>integration-lite-first</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>integration-lite-second</id>
+
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <logback.configurationFile>${project.basedir}/src/test/resources/logback-test.xml</logback.configurationFile>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
     <properties>
         <reactor-spring.version>1.0.1.RELEASE</reactor-spring.version>
         <johnzon.version>1.1.3</johnzon.version>
         <jsonb-api.version>1.0</jsonb-api.version>
         <geronimo-json_1.1_spec.version>1.0</geronimo-json_1.1_spec.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <jetty-reactive-httpclient.version>1.1.6</jetty-reactive-httpclient.version>
         <okhttp.version>4.0.1</okhttp.version>
     </properties>
-
 </project>
\ No newline at end of file
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/WebClientStatusCodeHandler.java b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/WebClientStatusCodeHandler.java
new file mode 100644
index 0000000000..9594ca32f1
--- /dev/null
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/WebClientStatusCodeHandler.java
@@ -0,0 +1,54 @@
+package com.baeldung.webclient.status;
+
+import com.baeldung.webclient.status.exception.BadRequestException;
+import com.baeldung.webclient.status.exception.ServerErrorException;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.ExchangeFilterFunction;
+import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Mono;
+
+public class WebClientStatusCodeHandler {
+
+    public static Mono<String> getResponseBodyUsingExchangeFilterFunction(String uri) {
+        ExchangeFilterFunction errorResponseFilter = ExchangeFilterFunction
+            .ofResponseProcessor(WebClientStatusCodeHandler::exchangeFilterResponseProcessor);
+        return WebClient
+            .builder()
+            .filter(errorResponseFilter)
+            .build()
+            .post()
+            .uri(uri)
+            .retrieve()
+            .bodyToMono(String.class);
+    }
+
+    public static Mono<String> getResponseBodyUsingOnStatus(String uri) {
+        return WebClient
+            .builder()
+            .build()
+            .post()
+            .uri(uri)
+            .retrieve()
+            .onStatus(
+                HttpStatus.INTERNAL_SERVER_ERROR::equals,
+                response -> response.bodyToMono(String.class).map(ServerErrorException::new))
+            .onStatus(
+                HttpStatus.BAD_REQUEST::equals,
+                response -> response.bodyToMono(String.class).map(BadRequestException::new))
+            .bodyToMono(String.class);
+    }
+
+    private static Mono<ClientResponse> exchangeFilterResponseProcessor(ClientResponse response) {
+        HttpStatus status = response.statusCode();
+        if (HttpStatus.INTERNAL_SERVER_ERROR.equals(status)) {
+            return response.bodyToMono(String.class)
+                .flatMap(body -> Mono.error(new ServerErrorException(body)));
+        }
+        if (HttpStatus.BAD_REQUEST.equals(status)) {
+            return response.bodyToMono(String.class)
+                .flatMap(body -> Mono.error(new BadRequestException(body)));
+        }
+        return Mono.just(response);
+    }
+}
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/BadRequestException.java b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/BadRequestException.java
new file mode 100644
index 0000000000..bf5c599805
--- /dev/null
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/BadRequestException.java
@@ -0,0 +1,7 @@
+package com.baeldung.webclient.status.exception;
+
+public class BadRequestException extends Exception {
+    public BadRequestException(String message) {
+        super(message);
+    }
+}
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/ServerErrorException.java b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/ServerErrorException.java
new file mode 100644
index 0000000000..7e97f17dff
--- /dev/null
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/webclient/status/exception/ServerErrorException.java
@@ -0,0 +1,7 @@
+package com.baeldung.webclient.status.exception;
+
+public class ServerErrorException extends Exception {
+    public ServerErrorException(String message) {
+        super(message);
+    }
+}
diff --git a/spring-5-reactive-client/src/test/java/com/baeldung/webclient/WebClientStatusCodeHandlerIntegrationTest.java b/spring-5-reactive-client/src/test/java/com/baeldung/webclient/WebClientStatusCodeHandlerIntegrationTest.java
new file mode 100644
index 0000000000..e491baf97a
--- /dev/null
+++ b/spring-5-reactive-client/src/test/java/com/baeldung/webclient/WebClientStatusCodeHandlerIntegrationTest.java
@@ -0,0 +1,98 @@
+package com.baeldung.webclient;
+
+import com.baeldung.webclient.status.WebClientStatusCodeHandler;
+import com.github.tomakehurst.wiremock.WireMockServer;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.test.context.junit4.SpringRunner;
+import reactor.core.publisher.Mono;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.configureFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.post;
+import static com.github.tomakehurst.wiremock.client.WireMock.stubFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo;
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
+import static java.lang.String.format;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@RunWith(SpringRunner.class)
+public class WebClientStatusCodeHandlerIntegrationTest {
+    private String baseUrl;
+    private WireMockServer wireMockServer;
+
+    @Before
+    public void setUp() {
+        wireMockServer = new WireMockServer(wireMockConfig().dynamicPort());
+        wireMockServer.start();
+        configureFor("localhost", wireMockServer.port());
+        baseUrl = format("http://localhost:%s", wireMockServer.port());
+    }
+
+    @After
+    public void tearDown() {
+        wireMockServer.stop();
+    }
+
+    @Test
+    public void whenResponseIs2XX_thenBothStatusHandlerAndExchangeFilterReturnEqualResponses() {
+        stubPostResponse("/success", 200, "success");
+
+        Mono<String> responseStatusHandler = WebClientStatusCodeHandler
+            .getResponseBodyUsingOnStatus(baseUrl + "/success");
+
+        Mono<String> responseExchangeFilter = WebClientStatusCodeHandler
+           .getResponseBodyUsingExchangeFilterFunction(baseUrl + "/success");
+
+        assertThat(responseStatusHandler.block())
+            .isEqualTo(responseExchangeFilter.block())
+            .isEqualTo("success");
+    }
+
+    @Test
+    public void whenResponseIs500_thenBothStatusHandlerAndExchangeFilterReturnEqualResponses() {
+        stubPostResponse("/server-error", 500, "Internal Server Error");
+
+        Mono<String> responseStatusHandler = WebClientStatusCodeHandler
+            .getResponseBodyUsingOnStatus(baseUrl + "/server-error");
+
+        Mono<String> responseExchangeFilter = WebClientStatusCodeHandler
+            .getResponseBodyUsingExchangeFilterFunction(baseUrl + "/server-error");
+
+        assertThatThrownBy(responseStatusHandler::block)
+            .isInstanceOf(Exception.class)
+            .hasMessageContaining("Internal Server Error");
+
+        assertThatThrownBy(responseExchangeFilter::block)
+            .isInstanceOf(Exception.class)
+            .hasMessageContaining("Internal Server Error");
+    }
+
+    @Test
+    public void whenResponseIs400_thenBothStatusHandlerAndExchangeFilterReturnEqualResponses() {
+        stubPostResponse("/client-error", 400, "Bad Request");
+
+        Mono<String> responseStatusHandler = WebClientStatusCodeHandler
+            .getResponseBodyUsingOnStatus(baseUrl + "/client-error");
+
+        Mono<String> responseExchangeFilter = WebClientStatusCodeHandler
+            .getResponseBodyUsingExchangeFilterFunction(baseUrl + "/client-error");
+
+        assertThatThrownBy(responseStatusHandler::block)
+            .isInstanceOf(Exception.class)
+            .hasMessageContaining("Bad Request");
+
+        assertThatThrownBy(responseExchangeFilter::block)
+            .isInstanceOf(Exception.class)
+            .hasMessageContaining("Bad Request");
+    }
+
+    private static void stubPostResponse(String url, int statusCode, String response) {
+        stubFor(post(urlEqualTo(url)).willReturn(aResponse()
+            .withStatus(statusCode)
+            .withBody(response)));
+    }
+}
\ No newline at end of file
diff --git a/spring-5-reactive-security/pom.xml b/spring-5-reactive-security/pom.xml
index 267a683fa7..140c6b8296 100644
--- a/spring-5-reactive-security/pom.xml
+++ b/spring-5-reactive-security/pom.xml
@@ -123,7 +123,6 @@
         <johnzon.version>1.1.3</johnzon.version>
         <jsonb-api.version>1.0</jsonb-api.version>
         <geronimo-json_1.1_spec.version>1.0</geronimo-json_1.1_spec.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <project-reactor-test>3.1.6.RELEASE</project-reactor-test>
     </properties>
 
diff --git a/spring-5-reactive/pom.xml b/spring-5-reactive/pom.xml
index 408573198b..b9456c7181 100644
--- a/spring-5-reactive/pom.xml
+++ b/spring-5-reactive/pom.xml
@@ -153,7 +153,6 @@
         <johnzon.version>1.1.3</johnzon.version>
         <jsonb-api.version>1.0</jsonb-api.version>
         <geronimo-json_1.1_spec.version>1.0</geronimo-json_1.1_spec.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/spring-5-webflux/README.md b/spring-5-webflux/README.md
index bd667468fb..889f211fc6 100644
--- a/spring-5-webflux/README.md
+++ b/spring-5-webflux/README.md
@@ -11,3 +11,4 @@ This module contains articles about Spring 5 WebFlux
 - [Spring MVC Async vs Spring WebFlux](https://www.baeldung.com/spring-mvc-async-vs-webflux)
 - [Set a Timeout in Spring 5 Webflux WebClient](https://www.baeldung.com/spring-webflux-timeout)
 - [Guide to Retry in Spring WebFlux](https://www.baeldung.com/spring-webflux-retry)
+- [Spring Webflux and @Cacheable Annotation](https://www.baeldung.com/spring-webflux-cacheable)
diff --git a/spring-5/pom.xml b/spring-5/pom.xml
index 5799f3bc8f..1ac696e7bd 100644
--- a/spring-5/pom.xml
+++ b/spring-5/pom.xml
@@ -142,7 +142,6 @@
     <properties>
         <geronimo-json_1.1_spec.version>1.0</geronimo-json_1.1_spec.version>
         <asciidoctor-plugin.version>1.5.6</asciidoctor-plugin.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <snippetsDirectory>${project.build.directory}/generated-snippets</snippetsDirectory>
         <hikaricp.version>4.0.3</hikaricp.version>
     </properties>
diff --git a/spring-boot-modules/spring-boot-basic-customization-2/README.md b/spring-boot-modules/spring-boot-basic-customization-2/README.md
index 0e688bda2a..9488618ca5 100644
--- a/spring-boot-modules/spring-boot-basic-customization-2/README.md
+++ b/spring-boot-modules/spring-boot-basic-customization-2/README.md
@@ -7,3 +7,4 @@ This module contains articles about Spring Boot customization 2
  - [DispatcherServlet and web.xml in Spring Boot](https://www.baeldung.com/spring-boot-dispatcherservlet-web-xml)
  - [XML Defined Beans in Spring Boot](https://www.baeldung.com/spring-boot-xml-beans)
  - [What Is OncePerRequestFilter?](https://www.baeldung.com/spring-onceperrequestfilter)
+ - [Spring Boot Exit Codes](https://www.baeldung.com/spring-boot-exit-codes)
diff --git a/spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/event/ExitCodeEventDemoApplication.java b/spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/event/ExitCodeEventDemoApplication.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/event/ExitCodeEventDemoApplication.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/event/ExitCodeEventDemoApplication.java
diff --git a/spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exception/ExitCodeExceptionMapperDemoApplication.java b/spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exception/ExitCodeExceptionMapperDemoApplication.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exception/ExitCodeExceptionMapperDemoApplication.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exception/ExitCodeExceptionMapperDemoApplication.java
diff --git a/spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exceptionexitgen/ExceptionExitCodeGeneratorApplication.java b/spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exceptionexitgen/ExceptionExitCodeGeneratorApplication.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exceptionexitgen/ExceptionExitCodeGeneratorApplication.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exceptionexitgen/ExceptionExitCodeGeneratorApplication.java
diff --git a/spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exceptionexitgen/FailedToStartException.java b/spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exceptionexitgen/FailedToStartException.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/exceptionexitgen/FailedToStartException.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/exceptionexitgen/FailedToStartException.java
diff --git a/spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/generator/ExitCodeGeneratorDemoApplication.java b/spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/generator/ExitCodeGeneratorDemoApplication.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/exitcode/generator/ExitCodeGeneratorDemoApplication.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/main/java/com/baeldung/exitcode/generator/ExitCodeGeneratorDemoApplication.java
diff --git a/spring-boot-modules/spring-boot-basic-customization-2/src/main/test/com/baeldung/springbootxml/SpringBootXmlApplicationIntegrationTest.java b/spring-boot-modules/spring-boot-basic-customization-2/src/test/java/com/baeldung/springbootxml/SpringBootXmlApplicationIntegrationTest.java
similarity index 100%
rename from spring-boot-modules/spring-boot-basic-customization-2/src/main/test/com/baeldung/springbootxml/SpringBootXmlApplicationIntegrationTest.java
rename to spring-boot-modules/spring-boot-basic-customization-2/src/test/java/com/baeldung/springbootxml/SpringBootXmlApplicationIntegrationTest.java
diff --git a/spring-boot-modules/spring-boot-basic-customization/README.md b/spring-boot-modules/spring-boot-basic-customization/README.md
index 6c067fc5a1..a3d9f1b1fc 100644
--- a/spring-boot-modules/spring-boot-basic-customization/README.md
+++ b/spring-boot-modules/spring-boot-basic-customization/README.md
@@ -11,4 +11,3 @@ This module contains articles about Spring Boot customization
  - [Spring Boot: Configuring a Main Class](https://www.baeldung.com/spring-boot-main-class)
  - [How to Define a Spring Boot Filter?](https://www.baeldung.com/spring-boot-add-filter)
  - [Guide to the Favicon in Spring Boot](https://www.baeldung.com/spring-boot-favicon)
- - [Spring Boot Exit Codes](https://www.baeldung.com/spring-boot-exit-codes)
diff --git a/spring-boot-modules/spring-boot-runtime/README.md b/spring-boot-modules/spring-boot-runtime/README.md
index 94822af09e..6f21efe793 100644
--- a/spring-boot-modules/spring-boot-runtime/README.md
+++ b/spring-boot-modules/spring-boot-runtime/README.md
@@ -10,4 +10,3 @@ This module contains articles about administering a Spring Boot runtime
  - [Project Configuration with Spring](https://www.baeldung.com/project-configuration-with-spring)
  - [Spring – Log Incoming Requests](https://www.baeldung.com/spring-http-logging)
  - [How to Configure Spring Boot Tomcat](https://www.baeldung.com/spring-boot-configure-tomcat)
- - [Max-HTTP-Header-Size in Spring Boot 2](https://www.baeldung.com/spring-boot-max-http-header-size)
diff --git a/spring-boot-modules/spring-boot-swagger/pom.xml b/spring-boot-modules/spring-boot-swagger/pom.xml
index 87ee5f04cb..d6b62bce3c 100644
--- a/spring-boot-modules/spring-boot-swagger/pom.xml
+++ b/spring-boot-modules/spring-boot-swagger/pom.xml
@@ -40,4 +40,4 @@
         <springfox.version>3.0.0</springfox.version>
     </properties>
 
-</project>
\ No newline at end of file
+</project>
diff --git a/spring-boot-rest-2/README.md b/spring-boot-rest-2/README.md
index 41270d58ea..985aa97a86 100644
--- a/spring-boot-rest-2/README.md
+++ b/spring-boot-rest-2/README.md
@@ -2,3 +2,4 @@
 
 - [Get All Endpoints in Spring Boot](https://www.baeldung.com/spring-boot-get-all-endpoints)
 - [HTTP PUT vs. POST in REST API](https://www.baeldung.com/rest-http-put-vs-post)
+- [415 Unsupported MediaType in Spring Application](https://www.baeldung.com/spring-415-unsupported-mediatype)
diff --git a/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UnsupportedMediaTypeApplication.java b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UnsupportedMediaTypeApplication.java
new file mode 100644
index 0000000000..2bf6bb33cd
--- /dev/null
+++ b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UnsupportedMediaTypeApplication.java
@@ -0,0 +1,13 @@
+package com.baeldung.unsupportedmediatype;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class UnsupportedMediaTypeApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(UnsupportedMediaTypeApplication.class, args);
+    }
+
+}
diff --git a/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/User.java b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/User.java
new file mode 100644
index 0000000000..765149dad5
--- /dev/null
+++ b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/User.java
@@ -0,0 +1,66 @@
+package com.baeldung.unsupportedmediatype;
+
+import javax.xml.bind.annotation.XmlRootElement;
+import java.io.Serializable;
+
+@XmlRootElement
+public class User implements Serializable {
+    private Integer id;
+    private String name;
+    private Integer age;
+    private String address;
+
+    public User(){
+    }
+
+    public User(Integer id, String name, Integer age, String address) {
+        this.id = id;
+        this.name = name;
+        this.age = age;
+        this.address = address;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    @Override
+    public String toString() {
+        return  "User{"
+          + "id=" + id
+          + ", name='" + name + '\''
+          + ", age=" + age
+          + ", address='" + address + '\''
+          + '}';
+    }
+
+
+}
diff --git a/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UserController.java b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UserController.java
new file mode 100644
index 0000000000..a20043619a
--- /dev/null
+++ b/spring-boot-rest-2/src/main/java/com/baeldung/unsupportedmediatype/UserController.java
@@ -0,0 +1,29 @@
+package com.baeldung.unsupportedmediatype;
+
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.Collections;
+import java.util.List;
+
+@RestController
+@RequestMapping("/user")
+public class UserController {
+
+    @GetMapping(value = "/")
+    List<User> getAllUsers(){
+        return Collections.singletonList(new User(1, "Andy", 28, "14th Street"));
+    }
+
+    @GetMapping(value = "/{user-id}")
+    User getUser(@PathVariable("user-id") Integer userId){
+        return new User(userId, "Andy", 28, "14th Street");
+    }
+
+    @PostMapping(value = "/", consumes = {MediaType.APPLICATION_XML_VALUE, MediaType.APPLICATION_JSON_VALUE})
+    void AddUser(@RequestBody User user){
+        // Adding the User in the repository
+    }
+
+
+}
\ No newline at end of file
diff --git a/spring-boot-rest-2/src/test/java/com/baeldung/unsupportedmediatype/ApplicationUnitTest.java b/spring-boot-rest-2/src/test/java/com/baeldung/unsupportedmediatype/ApplicationUnitTest.java
new file mode 100644
index 0000000000..498ad9d537
--- /dev/null
+++ b/spring-boot-rest-2/src/test/java/com/baeldung/unsupportedmediatype/ApplicationUnitTest.java
@@ -0,0 +1,58 @@
+package com.baeldung.unsupportedmediatype;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
+
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@RunWith(SpringRunner.class)
+@WebMvcTest(UserController.class)
+public class ApplicationUnitTest {
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    public void JsonTestCase() throws Exception {
+        mockMvc.perform(MockMvcRequestBuilders.post("/user/")
+          .contentType(MediaType.APPLICATION_JSON_VALUE)
+          .content(  "{\n"
+          + "    \"name\": \"Andy\",\n"
+          + "    \"age\": 1,\n"
+          + "    \"address\": \"Hello world\"\n"
+          + "}"))
+          .andExpect(status().isOk());
+    }
+
+    @Test
+    public void JsonFailTestCase() throws Exception {// Because no content-type added
+        mockMvc.perform(MockMvcRequestBuilders.post("/user/")
+          .content(  "{\n"
+          + "    \"name\": \"Andy\",\n"
+          + "    \"age\": 1,\n"
+          + "    \"address\": \"Hello world\"\n"
+          + "}"))
+          .andExpect(status().isUnsupportedMediaType());
+    }
+
+    @Test
+    public void XmlTestCase() throws Exception {
+        mockMvc.perform(MockMvcRequestBuilders.post("/user/")
+          .contentType(MediaType.APPLICATION_XML_VALUE)
+          .content("<user><name>Andy</name><age>1</age><address>Hello world</address></user>"))
+          .andExpect(status().isOk());
+    }
+
+    @Test
+    public void StringFailTestCase() throws Exception { // Because content-type is not supported
+        mockMvc.perform(MockMvcRequestBuilders.post("/user/")
+          .contentType(MediaType.TEXT_PLAIN_VALUE)
+          .content("<user><name>Andy</name><age>1</age><address>Hello world</address></user>"))
+          .andExpect(status().isUnsupportedMediaType());
+    }
+}
diff --git a/spring-cloud-bus/spring-cloud-config-client/src/main/resources/application.yml b/spring-cloud-bus/spring-cloud-config-client/src/main/resources/application.yml
index fbbc6d138f..bb5c9607b8 100644
--- a/spring-cloud-bus/spring-cloud-config-client/src/main/resources/application.yml
+++ b/spring-cloud-bus/spring-cloud-config-client/src/main/resources/application.yml
@@ -1,5 +1,11 @@
 ---
 spring:
+  application:
+    name: config-client
+  profiles:
+    active: development
+  config:
+    import: configserver:http://root:s3cr3t@localhost:8888
   rabbitmq:
     host: localhost
     port: 5672
@@ -10,8 +16,12 @@ spring:
       enabled: true
       refresh:
         enabled: true
+    config:
+      fail-fast: true
 management:
   endpoints:
     web:
       exposure:
-        include: "*"
\ No newline at end of file
+        include: "*"
+  security:
+    enabled: false
\ No newline at end of file
diff --git a/spring-cloud-bus/spring-cloud-config-client/src/main/resources/bootstrap.properties b/spring-cloud-bus/spring-cloud-config-client/src/main/resources/bootstrap.properties
deleted file mode 100644
index 7b362614ba..0000000000
--- a/spring-cloud-bus/spring-cloud-config-client/src/main/resources/bootstrap.properties
+++ /dev/null
@@ -1,7 +0,0 @@
-spring.application.name=config-client
-spring.profiles.active=development
-spring.cloud.config.uri=http://localhost:8888
-spring.cloud.config.username=root
-spring.cloud.config.password=s3cr3t
-spring.cloud.config.fail-fast=true
-management.security.enabled=false
\ No newline at end of file
diff --git a/spring-cloud-bus/spring-cloud-config-server/src/main/resources/application.properties b/spring-cloud-bus/spring-cloud-config-server/src/main/resources/application.properties
index 6d7a945612..00ef9f0217 100644
--- a/spring-cloud-bus/spring-cloud-config-server/src/main/resources/application.properties
+++ b/spring-cloud-bus/spring-cloud-config-server/src/main/resources/application.properties
@@ -6,4 +6,9 @@ spring.security.user.password=s3cr3t
 spring.rabbitmq.host=localhost
 spring.rabbitmq.port=5672
 spring.rabbitmq.username=guest
-spring.rabbitmq.password=guest
\ No newline at end of file
+spring.rabbitmq.password=guest
+
+encrypt.key-store.location=classpath:/config-server.jks
+encrypt.key-store.password=my-s70r3-s3cr3t
+encrypt.key-store.alias=config-server-key
+encrypt.key-store.secret=my-k34-s3cr3t
\ No newline at end of file
diff --git a/spring-cloud-bus/spring-cloud-config-server/src/main/resources/bootstrap.properties b/spring-cloud-bus/spring-cloud-config-server/src/main/resources/bootstrap.properties
deleted file mode 100644
index b0c35c72a6..0000000000
--- a/spring-cloud-bus/spring-cloud-config-server/src/main/resources/bootstrap.properties
+++ /dev/null
@@ -1,4 +0,0 @@
-encrypt.key-store.location=classpath:/config-server.jks
-encrypt.key-store.password=my-s70r3-s3cr3t
-encrypt.key-store.alias=config-server-key
-encrypt.key-store.secret=my-k34-s3cr3t
\ No newline at end of file
diff --git a/spring-cloud/spring-cloud-config/client/src/main/resources/application.properties b/spring-cloud/spring-cloud-config/client/src/main/resources/application.properties
index 6366bc515c..a96e6189a1 100644
--- a/spring-cloud/spring-cloud-config/client/src/main/resources/application.properties
+++ b/spring-cloud/spring-cloud-config/client/src/main/resources/application.properties
@@ -1,3 +1,3 @@
 spring.application.name=config-client
 spring.profiles.active=development
-spring.config.import=optional:configserver:http://root:s3cr3t@localhost:8888 
\ No newline at end of file
+spring.config.import=optional:configserver:http://root:s3cr3t@localhost:8888
\ No newline at end of file
diff --git a/spring-cloud/spring-cloud-vault/pom.xml b/spring-cloud/spring-cloud-vault/pom.xml
index 131d58c967..3f72ac9fe2 100644
--- a/spring-cloud/spring-cloud-vault/pom.xml
+++ b/spring-cloud/spring-cloud-vault/pom.xml
@@ -78,7 +78,7 @@
     </build>
 
     <properties>
-        <spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>
+        <spring-cloud.version>2020.0.3</spring-cloud.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/spring-cloud/spring-cloud-vault/src/main/resources/application.yml b/spring-cloud/spring-cloud-vault/src/main/resources/application.yml
index 1c75ac21e6..cb0b2d60fd 100644
--- a/spring-cloud/spring-cloud-vault/src/main/resources/application.yml
+++ b/spring-cloud/spring-cloud-vault/src/main/resources/application.yml
@@ -1,11 +1,34 @@
-spring:
-  application:
-    name: fakebank
-    
-  datasource:
-    url: jdbc:mysql://localhost:3306/fakebank?serverTimezone=GMT-3
-    hikari:
      connection-test-query: select 1
-      idle-timeout: 5000
-      max-lifetime: 120000
-      maximum-pool-size: 5
-      minimum-idle: 5
+spring:
+  application:
+    name: fakebank
+  datasource:
+    url: jdbc:mysql://localhost:3306/fakebank?serverTimezone=GMT-3
+    hikari:
+      connection-test-query: select 1
+      idle-timeout: 5000
+      max-lifetime: 120000
+      maximum-pool-size: 5
+      minimum-idle: 5
+  cloud:
+    vault:
+      uri: https://localhost:8200
+      connection-timeout: 5000
+      read-timeout: 15000
+      ssl:
+        trust-store: classpath:/vault.jks
+        trust-store-password: changeit
+      generic:
+        enabled: true
+        application-name: fakebank
+      #      kv:
+      #        enabled: false
+      #        backend: kv
+      #        application-name: fakebank
+      database:
+        enabled: true
+        role: fakebank-accounts-ro
+        backend: database
+        username-property: spring.datasource.username
+        password-property: spring.datasource.password
+  config:
+    import: vault://
\ No newline at end of file
diff --git a/spring-cloud/spring-cloud-vault/src/main/resources/bootstrap.yml b/spring-cloud/spring-cloud-vault/src/main/resources/bootstrap.yml
deleted file mode 100644
index 7d38b06c0f..0000000000
--- a/spring-cloud/spring-cloud-vault/src/main/resources/bootstrap.yml
+++ /dev/null
@@ -1,37 +0,0 @@
-spring:
-  cloud:
-    vault:
-      uri: https://localhost:8200
-      connection-timeout: 5000
-      read-timeout: 15000
-          
-      ssl:
-        trust-store: classpath:/vault.jks
-        trust-store-password: changeit
-      
-      generic:
-        enabled: true
-        application-name: fakebank
-        
-#      kv:
-#        enabled: false
-#        backend: kv
-#        application-name: fakebank
-#        
-      database:
-        enabled: true
-        role: fakebank-accounts-rw
-        backend: database
-        username-property: spring.datasource.username
-        password-property: spring.datasource.password
-#
-#        
-        
-              
-        
-      
-      
-        
-      
-          
-          
\ No newline at end of file
diff --git a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Camelcase.java b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Capitalized.java
similarity index 74%
rename from spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Camelcase.java
rename to spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Capitalized.java
index b0b0b739e2..de83297c53 100644
--- a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Camelcase.java
+++ b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/Capitalized.java
@@ -5,12 +5,12 @@ import javax.validation.Payload;
 import java.lang.annotation.*;
 
 @Documented
-@Constraint(validatedBy = {CamelcaseValidator.class})
+@Constraint(validatedBy = {CapitalizedValidator.class})
 @Target({ElementType.PARAMETER, ElementType.FIELD, ElementType.METHOD})
 @Retention(RetentionPolicy.RUNTIME)
-public @interface Camelcase {
+public @interface Capitalized {
 
-    String message() default "Name should be uppercase.";
+    String message() default "Name should be capitalized.";
 
     boolean required() default true;
 
diff --git a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CamelcaseValidator.java b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CapitalizedValidator.java
similarity index 83%
rename from spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CamelcaseValidator.java
rename to spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CapitalizedValidator.java
index 2b08e3dd2a..969dc0c56c 100644
--- a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CamelcaseValidator.java
+++ b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/java/com/baeldung/openapi/petstore/validation/CapitalizedValidator.java
@@ -4,11 +4,11 @@ import javax.validation.ConstraintValidator;
 import javax.validation.ConstraintValidatorContext;
 import java.util.Objects;
 
-public class CamelcaseValidator implements ConstraintValidator<Camelcase, String> {
+public class CapitalizedValidator implements ConstraintValidator<Capitalized, String> {
 
-	private Camelcase uppercaseAnnotation;
+	private Capitalized uppercaseAnnotation;
 
-	public void initialize(Camelcase constraintAnnotation) {
+	public void initialize(Capitalized constraintAnnotation) {
 		this.uppercaseAnnotation = constraintAnnotation;
 	}
 
diff --git a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/api.mustache b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/api.mustache
index a7a35d43b5..34f4afac3a 100644
--- a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/api.mustache
+++ b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/api.mustache
@@ -8,7 +8,7 @@ package {{package}};
 {{#imports}}import {{import}};
 {{/imports}}
 import io.swagger.annotations.*;
-import com.baeldung.openapi.petstore.validation.Camelcase;
+import com.baeldung.openapi.petstore.validation.Capitalized;
 {{#jdk8-no-delegate}}
 {{#virtualService}}
 import io.virtualan.annotation.ApiVirtual;
diff --git a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/model.mustache b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/model.mustache
index d9329b40d3..4546a811ef 100644
--- a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/model.mustache
+++ b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/openapi/templates/model.mustache
@@ -4,7 +4,7 @@ package {{package}};
 {{/imports}}
 import com.fasterxml.jackson.databind.annotation.*;
 import com.fasterxml.jackson.annotation.*;
-import com.baeldung.openapi.petstore.validation.Camelcase;
+import com.baeldung.openapi.petstore.validation.Capitalized;
 {{^supportJava6}}
 import java.util.Objects;
 import java.util.Arrays;
diff --git a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/petstore.yml b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/petstore.yml
index c9884c01e8..c5fbd830bb 100644
--- a/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/petstore.yml
+++ b/spring-swagger-codegen/custom-validations-opeanpi-codegen/src/main/resources/petstore.yml
@@ -37,7 +37,7 @@ paths:
           schema:
             type: string
           description: Tags to filter by
-          x-constraints: "@Camelcase(required = true)"
+          x-constraints: "@Capitalized(required = true)"
       responses:
         '200':
           description: default response
@@ -62,4 +62,4 @@ components:
           format: int64
         name:
           type: string
-          x-constraints: "@Camelcase(required = true)"
\ No newline at end of file
+          x-constraints: "@Capitalized(required = true)"
\ No newline at end of file
diff --git a/spring-websockets/README.md b/spring-websockets/README.md
index 7d69c21b78..88a97850b5 100644
--- a/spring-websockets/README.md
+++ b/spring-websockets/README.md
@@ -7,3 +7,4 @@ This module contains articles about Spring WebSockets.
 - [A Quick Example of Spring Websockets’ @SendToUser Annotation](https://www.baeldung.com/spring-websockets-sendtouser)
 - [Scheduled WebSocket Push with Spring Boot](https://www.baeldung.com/spring-boot-scheduled-websocket)
 - [Test WebSocket APIs With Postman](https://www.baeldung.com/postman-websocket-apis)
+- [Debugging WebSockets](https://www.baeldung.com/debug-websockets)
diff --git a/spring-websockets/pom.xml b/spring-websockets/pom.xml
index a28ef8749a..28c875d50d 100644
--- a/spring-websockets/pom.xml
+++ b/spring-websockets/pom.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>spring-websockets</artifactId>
     <name>spring-websockets</name>
diff --git a/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StockTicksController.java b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StockTicksController.java
new file mode 100644
index 0000000000..0942657c33
--- /dev/null
+++ b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StockTicksController.java
@@ -0,0 +1,39 @@
+package com.baeldung.debugwebsockets;
+
+import org.springframework.messaging.simp.SimpMessagingTemplate;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Controller;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
+
+@Controller
+public class StockTicksController {
+    private final SimpMessagingTemplate simpMessagingTemplate;
+
+    public StockTicksController(SimpMessagingTemplate simpMessagingTemplate) {
+        this.simpMessagingTemplate = simpMessagingTemplate;
+    }
+
+    @Scheduled(fixedRate = 3000)
+    public void sendTicks() {
+        simpMessagingTemplate.convertAndSend("/topic/ticks", getStockTicks());
+    }
+
+    private Map<String, Integer> getStockTicks() {
+        Map<String, Integer> ticks = new HashMap<>();
+        ticks.put("AAPL", getRandomTick());
+        ticks.put("GOOGL", getRandomTick());
+        ticks.put("MSFT", getRandomTick());
+        ticks.put("TSLA", getRandomTick());
+        ticks.put("AMZN", getRandomTick());
+        ticks.put("HPE", getRandomTick());
+
+        return ticks;
+    }
+
+    private int getRandomTick() {
+        return ThreadLocalRandom.current().nextInt(-100, 100 + 1);
+    }
+}
\ No newline at end of file
diff --git a/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompClientSessionHandler.java b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompClientSessionHandler.java
new file mode 100644
index 0000000000..535be79cee
--- /dev/null
+++ b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompClientSessionHandler.java
@@ -0,0 +1,31 @@
+package com.baeldung.debugwebsockets;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.messaging.simp.stomp.StompHeaders;
+import org.springframework.messaging.simp.stomp.StompSession;
+import org.springframework.messaging.simp.stomp.StompSessionHandlerAdapter;
+
+import java.lang.reflect.Type;
+import java.util.Map;
+
+public class StompClientSessionHandler extends StompSessionHandlerAdapter {
+    private static final Logger logger = LoggerFactory.getLogger("StompClientSessionHandler");
+
+    @Override
+    public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
+        logger.info("New session established. Session Id -> {}", session.getSessionId());
+        session.subscribe("/topic/ticks", this);
+        logger.info("Subscribed to topic: /topic/ticks");
+    }
+
+    @Override
+    public void handleFrame(StompHeaders headers, Object payload) {
+        logger.info("Payload -> {}", payload);
+    }
+
+    @Override
+    public Type getPayloadType(StompHeaders headers) {
+        return Map.class;
+    }
+}
diff --git a/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompWebSocketClient.java b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompWebSocketClient.java
new file mode 100644
index 0000000000..0cbe32bf65
--- /dev/null
+++ b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompWebSocketClient.java
@@ -0,0 +1,24 @@
+package com.baeldung.debugwebsockets;
+
+import org.springframework.messaging.converter.MappingJackson2MessageConverter;
+import org.springframework.messaging.simp.stomp.StompSessionHandler;
+import org.springframework.web.socket.client.WebSocketClient;
+import org.springframework.web.socket.client.standard.StandardWebSocketClient;
+import org.springframework.web.socket.messaging.WebSocketStompClient;
+
+import java.util.Scanner;
+
+public class StompWebSocketClient {
+
+    private static final String URL = "ws://localhost:8080/stock-ticks/websocket";
+
+    public static void main(String[] args) {
+        WebSocketClient client = new StandardWebSocketClient();
+        WebSocketStompClient stompClient = new WebSocketStompClient(client);
+        stompClient.setMessageConverter(new MappingJackson2MessageConverter());
+        StompSessionHandler sessionHandler = new StompClientSessionHandler();
+        stompClient.connect(URL, sessionHandler);
+
+        new Scanner(System.in).nextLine();
+    }
+}
diff --git a/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketApplication.java b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketApplication.java
new file mode 100644
index 0000000000..1d0d6950d3
--- /dev/null
+++ b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketApplication.java
@@ -0,0 +1,13 @@
+package com.baeldung.debugwebsockets;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class WebsocketApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(WebsocketApplication.class, args);
+    }
+
+}
diff --git a/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketConfiguration.java b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketConfiguration.java
new file mode 100644
index 0000000000..3735e7359b
--- /dev/null
+++ b/spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketConfiguration.java
@@ -0,0 +1,25 @@
+package com.baeldung.debugwebsockets;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.messaging.simp.config.MessageBrokerRegistry;
+import org.springframework.scheduling.annotation.EnableScheduling;
+import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
+import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
+import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
+
+@Configuration
+@EnableWebSocketMessageBroker
+@EnableScheduling
+public class WebsocketConfiguration implements WebSocketMessageBrokerConfigurer {
+    @Override
+    public void configureMessageBroker(MessageBrokerRegistry config) {
+        config.enableSimpleBroker("/topic");
+        config.setApplicationDestinationPrefixes("/app");
+    }
+
+    @Override
+    public void registerStompEndpoints(StompEndpointRegistry registry) {
+        registry.addEndpoint("/stock-ticks").setAllowedOriginPatterns("*").withSockJS();
+    }
+
+}
diff --git a/spring-websockets/src/test/java/com/baeldung/debugwebsockets/WebSocketIntegrationTest.java b/spring-websockets/src/test/java/com/baeldung/debugwebsockets/WebSocketIntegrationTest.java
new file mode 100644
index 0000000000..bdc283b9e4
--- /dev/null
+++ b/spring-websockets/src/test/java/com/baeldung/debugwebsockets/WebSocketIntegrationTest.java
@@ -0,0 +1,114 @@
+package com.baeldung.debugwebsockets;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.messaging.converter.MappingJackson2MessageConverter;
+import org.springframework.messaging.simp.stomp.StompCommand;
+import org.springframework.messaging.simp.stomp.StompFrameHandler;
+import org.springframework.messaging.simp.stomp.StompHeaders;
+import org.springframework.messaging.simp.stomp.StompSession;
+import org.springframework.messaging.simp.stomp.StompSessionHandler;
+import org.springframework.web.socket.client.WebSocketClient;
+import org.springframework.web.socket.client.standard.StandardWebSocketClient;
+import org.springframework.web.socket.messaging.WebSocketStompClient;
+
+import java.lang.reflect.Type;
+import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+/**
+ * This should be part of integration test suite.
+ * The test starts the server and then connects to the WebSocket. Then verifies if the messages are received from the
+ * WebSocket.
+ * This test is inspired from: https://github.com/spring-guides/gs-messaging-stomp-websocket/blob/main/complete/src/test/java/com/example/messagingstompwebsocket/GreetingIntegrationTests.java
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class WebSocketIntegrationTest{
+    WebSocketClient client;
+    WebSocketStompClient stompClient;
+    @LocalServerPort
+    private int port;
+    private static final Logger logger= LoggerFactory.getLogger(WebSocketIntegrationTest.class);
+
+    @BeforeEach
+    public void setup() {
+        logger.info("Setting up the tests ...");
+        client = new StandardWebSocketClient();
+        stompClient = new WebSocketStompClient(client);
+        stompClient.setMessageConverter(new MappingJackson2MessageConverter());
+    }
+
+    @Test
+    void givenWebSocket_whenMessage_thenVerifyMessage() throws Exception {
+        final CountDownLatch latch = new CountDownLatch(1);
+        final AtomicReference<Throwable> failure = new AtomicReference<>();
+        StompSessionHandler sessionHandler = new StompSessionHandler() {
+            @Override
+            public Type getPayloadType(StompHeaders headers) {
+                return null;
+            }
+
+            @Override
+            public void handleFrame(StompHeaders headers, Object payload) {
+            }
+
+            @Override
+            public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
+                logger.info("Connected to the WebSocket ...");
+                session.subscribe("/topic/ticks", new StompFrameHandler() {
+                    @Override
+                    public Type getPayloadType(StompHeaders headers) {
+                        return Map.class;
+                    }
+
+                    @Override
+                    public void handleFrame(StompHeaders headers, Object payload) {
+                        try {
+
+                            assertThat(payload).isNotNull();
+                            assertThat(payload).isInstanceOf(Map.class);
+
+                            @SuppressWarnings("unchecked")
+                            Map<String, Integer> map = (Map<String, Integer>) payload;
+
+                            assertThat(map).containsKey("HPE");
+                            assertThat(map.get("HPE")).isInstanceOf(Integer.class);
+                        } catch (Throwable t) {
+                            failure.set(t);
+                            logger.error("There is an exception ", t);
+                        } finally {
+                            session.disconnect();
+                            latch.countDown();
+                        }
+
+                    }
+                });
+            }
+
+            @Override
+            public void handleException(StompSession session, StompCommand command, StompHeaders headers, byte[] payload, Throwable exception) {
+            }
+
+            @Override
+            public void handleTransportError(StompSession session, Throwable exception) {
+            }
+        };
+        stompClient.connect("ws://localhost:{port}/stock-ticks/websocket", sessionHandler, this.port);
+        if (latch.await(20, TimeUnit.SECONDS)) {
+            if (failure.get() != null) {
+                fail("Assertion Failed", failure.get());
+            }
+        } else {
+            fail("Could not receive the message on time");
+        }
+    }
+}
diff --git a/testing-modules/spring-testing-2/pom.xml b/testing-modules/spring-testing-2/pom.xml
index 82a9ed9599..6bdec33d96 100644
--- a/testing-modules/spring-testing-2/pom.xml
+++ b/testing-modules/spring-testing-2/pom.xml
@@ -63,7 +63,7 @@
     </build>
 
     <properties>
-        <testcontainers.version>1.12.2</testcontainers.version>
+        <testcontainers.version>1.16.2</testcontainers.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/ArticleTestFixtureLiveTest.java b/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/ArticleTestFixtureLiveTest.java
index bb3ad28365..2975104c14 100644
--- a/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/ArticleTestFixtureLiveTest.java
+++ b/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/ArticleTestFixtureLiveTest.java
@@ -4,13 +4,17 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 
+import java.util.List;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 @SpringBootTest
 @ActiveProfiles("pg")
 @ExtendWith(PostgreSQLExtension.class)
+@DirtiesContext
 public class ArticleTestFixtureLiveTest {
 
     @Autowired
@@ -23,8 +27,11 @@ public class ArticleTestFixtureLiveTest {
         article.setContent("Today's applications...");
 
         articleRepository.save(article);
-        Article persisted = articleRepository.findAll().get(0);
-        assertThat(persisted.getId()).isNotNull();
+
+        List<Article> allArticles = articleRepository.findAll();
+        assertThat(allArticles).hasSize(1);
+
+        Article persisted = allArticles.get(0);
         assertThat(persisted.getTitle()).isEqualTo("A Guide to @DynamicPropertySource in Spring");
         assertThat(persisted.getContent()).isEqualTo("Today's applications...");
     }
diff --git a/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/PostgreSQLExtension.java b/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/PostgreSQLExtension.java
index 8c08ad67d7..28aab34867 100644
--- a/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/PostgreSQLExtension.java
+++ b/testing-modules/spring-testing-2/src/test/java/com/baeldung/dynamicproperties/PostgreSQLExtension.java
@@ -18,14 +18,14 @@ public class PostgreSQLExtension implements BeforeAllCallback, AfterAllCallback
           .withExposedPorts(5432);
 
         postgres.start();
-        String jdbcUrl = String.format("jdbc:postgresql://localhost:%d/prop", postgres.getFirstMappedPort());
-        System.setProperty("spring.datasource.url", jdbcUrl);
-        System.setProperty("spring.datasource.username", "postgres");
-        System.setProperty("spring.datasource.password", "pass");
+
+        System.setProperty("spring.datasource.url", postgres.getJdbcUrl());
+        System.setProperty("spring.datasource.username", postgres.getUsername());
+        System.setProperty("spring.datasource.password", postgres.getPassword());
     }
 
     @Override
     public void afterAll(ExtensionContext context) {
-        postgres.stop();
+        // do nothing, Testcontainers handles container shutdown
     }
 }
diff --git a/testing-modules/testing-assertions/pom.xml b/testing-modules/testing-assertions/pom.xml
index 689ca35733..09f4291b78 100644
--- a/testing-modules/testing-assertions/pom.xml
+++ b/testing-modules/testing-assertions/pom.xml
@@ -26,8 +26,4 @@
         </dependency>
     </dependencies>
 
-    <properties>
-        <commons-collections4.version>4.4</commons-collections4.version>
-    </properties>
-
 </project>
\ No newline at end of file
diff --git a/video-tutorials/jackson-annotations/pom.xml b/video-tutorials/jackson-annotations/pom.xml
index 29f457964b..eaec50c1f7 100644
--- a/video-tutorials/jackson-annotations/pom.xml
+++ b/video-tutorials/jackson-annotations/pom.xml
@@ -116,7 +116,6 @@
         <!-- various -->
         <joda-time.version>2.9.6</joda-time.version>
         <gson.version>2.8.0</gson.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <!-- testing -->
         <rest-assured.version>3.0.1</rest-assured.version>
         <rest-assured-json-schema-validator.version>3.0.0</rest-assured-json-schema-validator.version>
diff --git a/xml/pom.xml b/xml/pom.xml
index 968682ee38..0764c9d145 100644
--- a/xml/pom.xml
+++ b/xml/pom.xml
@@ -355,7 +355,6 @@
         <jaxen.version>1.2.0</jaxen.version>
         <jdom2.version>2.0.6</jdom2.version>
         <joox.version>1.6.2</joox.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
         <jibx-version>1.2.4.5</jibx-version>
         <jaxb-api.version>2.3.1</jaxb-api.version>
         <jaxp-api.version>1.4.2</jaxp-api.version>