diff --git a/patterns/design-patterns-2/pom.xml b/patterns/design-patterns-2/pom.xml
index 2a0213065b..5c3e70b046 100644
--- a/patterns/design-patterns-2/pom.xml
+++ b/patterns/design-patterns-2/pom.xml
@@ -15,11 +15,29 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>org.jetbrains</groupId>
+            <artifactId>annotations</artifactId>
+            <version>${intellij.annotations.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
     </dependencies>
     
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
+        <intellij.annotations.version>16.0.2</intellij.annotations.version>
+        <commons-lang3.version>3.5</commons-lang3.version>
     </properties>
 </project>
diff --git a/core-java/src/main/java/com/baeldung/nulls/APIContracts.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/APIContracts.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/APIContracts.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/APIContracts.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/Assertions.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/Assertions.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/Assertions.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/Assertions.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/EmptyCollections.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/EmptyCollections.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/EmptyCollections.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/EmptyCollections.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
similarity index 78%
rename from core-java/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
index a3804f6af5..697d5e4959 100644
--- a/core-java/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
+++ b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/FindBugsAnnotations.java
@@ -1,11 +1,12 @@
 package com.baeldung.nulls;
 
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 
 public class FindBugsAnnotations {
 
-    public void accept(@Nonnull Object param) {
+    public void accept(@NotNull Object param) {
         System.out.println(param.toString());
     }
 
@@ -13,7 +14,7 @@ public class FindBugsAnnotations {
         System.out.println("Printing " + param);
     }
 
-    @Nonnull
+    @NotNull
     public Object process() throws Exception {
         Object result = doSomething();
         if (result == null) {
diff --git a/core-java/src/main/java/com/baeldung/nulls/Preconditions.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/Preconditions.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/Preconditions.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/Preconditions.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/PrimitivesAndWrapper.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/PrimitivesAndWrapper.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/PrimitivesAndWrapper.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/PrimitivesAndWrapper.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/UsingLombok.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingLombok.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/UsingLombok.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingLombok.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/UsingObjects.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingObjects.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/UsingObjects.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingObjects.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/UsingOptional.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingOptional.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/UsingOptional.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingOptional.java
diff --git a/core-java/src/main/java/com/baeldung/nulls/UsingStringUtils.java b/patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingStringUtils.java
similarity index 100%
rename from core-java/src/main/java/com/baeldung/nulls/UsingStringUtils.java
rename to patterns/design-patterns-2/src/main/java/com/baeldung/nulls/UsingStringUtils.java
diff --git a/core-java/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
similarity index 99%
rename from core-java/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
rename to patterns/design-patterns-2/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
index 3c524387a4..49655619f6 100644
--- a/core-java/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
+++ b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/PrimitivesAndWrapperUnitTest.java
@@ -1,10 +1,10 @@
 package com.baeldung.nulls;
 
+import org.junit.jupiter.api.Test;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import org.junit.jupiter.api.Test;
-
 class PrimitivesAndWrapperUnitTest {
 
     @Test
diff --git a/core-java/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java
similarity index 82%
rename from core-java/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java
rename to patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java
index c157ad6630..b322344aba 100644
--- a/core-java/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java
+++ b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingLombokUnitTest.java
@@ -1,10 +1,9 @@
 package com.baeldung.nulls;
 
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 class UsingLombokUnitTest {
 
diff --git a/core-java/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java
similarity index 84%
rename from core-java/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java
rename to patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java
index 6939caa4fb..e1f5a288e6 100644
--- a/core-java/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java
+++ b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingObjectsUnitTest.java
@@ -1,12 +1,11 @@
 package com.baeldung.nulls;
 
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
-
 class UsingObjectsUnitTest {
 
     private UsingObjects classUnderTest;
@@ -19,7 +18,7 @@ class UsingObjectsUnitTest {
     @Test
     public void whenArgIsNull_thenThrowException() {
 
-        assertThrows(Exception.class, () -> classUnderTest.accept(null));
+        assertThrows(NullPointerException.class, () -> classUnderTest.accept(null));
     }
 
     @Test
diff --git a/core-java/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
similarity index 99%
rename from core-java/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
rename to patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
index d9d245369b..8f896cedfa 100644
--- a/core-java/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
+++ b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingOptionalUnitTest.java
@@ -1,14 +1,14 @@
 package com.baeldung.nulls;
 
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Optional;
+
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.util.Optional;
-
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
-
 class UsingOptionalUnitTest {
 
     private UsingOptional classUnderTest;
diff --git a/core-java/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
similarity index 93%
rename from core-java/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
rename to patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
index 99b1dbe6b4..f7c51a7dc5 100644
--- a/core-java/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
+++ b/patterns/design-patterns-2/src/test/java/com/baeldung/nulls/UsingStringUtilsUnitTest.java
@@ -1,10 +1,9 @@
 package com.baeldung.nulls;
 
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 class UsingStringUtilsUnitTest {