[JAVA-32669] Move article out of core-java-collections-5 (#16327)

core-java-modules/core-java-collections-5/README.md

@@ -9,7 +9,6 @@
 - [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
 - [Remove Elements From a Queue Using Loop](https://www.baeldung.com/java-remove-elements-queue)
 - [Intro to Vector Class in Java](https://www.baeldung.com/java-vector-guide)
-- [HashSet toArray() Method in Java](https://www.baeldung.com/java-hashset-toarray)
 - [Time Complexity of Java Collections Sort in Java](https://www.baeldung.com/java-time-complexity-collections-sort)
 - [Check if List Contains at Least One Enum](https://www.baeldung.com/java-list-check-enum-presence)
 - [Comparison of for Loops and Iterators](https://www.baeldung.com/java-for-loops-vs-iterators)

core-java-modules/core-java-collections-5/pom.xml

@@ -55,8 +55,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>9</source>
-                    <target>9</target>
+                    <source>16</source>
+                    <target>16</target>
                 </configuration>
             </plugin>
         </plugins>

core-java-modules/core-java-collections-5/toarraymethod/ConvertingHashSetToArrayUnitTest.java

@@ -1,51 +0,0 @@
-package com.baeldung.toarraymethod;
-
-import org.junit.Test;
-
-import java.util.HashSet;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-
-public class ConvertingHashSetToArrayUnitTest {
-
-    @Test
-    public void givenStringHashSet_whenConvertedToArray_thenArrayContainsStringElements() {
-        HashSet<String> stringSet = new HashSet<>();
-        stringSet.add("Apple");
-        stringSet.add("Banana");
-        stringSet.add("Cherry");
-
-        // Convert the HashSet of Strings to an array of Strings
-        String[] stringArray = stringSet.toArray(new String[0]);
-
-        // Test that the array is of the correct length
-        assertEquals(3, stringArray.length);
-
-        for (String str : stringArray) {
-            assertTrue(stringSet.contains(str));
-        }
-    }
-
-    @Test
-    public void givenIntegerHashSet_whenConvertedToArray_thenArrayContainsIntegerElements() {
-        HashSet<Integer> integerSet = new HashSet<>();
-        integerSet.add(5);
-        integerSet.add(10);
-        integerSet.add(15);
-
-        // Convert the HashSet of Integers to an array of Integers
-        Integer[] integerArray = integerSet.toArray(new Integer[0]);
-
-        // Test that the array is of the correct length
-        assertEquals(3, integerArray.length);
-
-        for (Integer num : integerArray) {
-            assertTrue(integerSet.contains(num));
-        }
-
-        assertTrue(integerSet.contains(5));
-        assertTrue(integerSet.contains(10));
-        assertTrue(integerSet.contains(15));
-    }
-}