2 files changed, 8 insertions, 4 deletions
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/index/CloneGroup.java b/sonar-duplications/src/main/java/org/sonar/duplications/index/CloneGroup.java
index b840c2f55f0..818e018d4bb 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/index/CloneGroup.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/index/CloneGroup.java
@@ -23,6 +23,8 @@ import com.google.common.annotations.Beta;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 
+import javax.annotation.Nullable;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -134,8 +136,8 @@ public class CloneGroup {
    * Two groups are equal, if they have same length, same origins and contain same parts in same order.
    */
   @Override
-  public boolean equals(Object object) {
-    if (this.getClass() != object.getClass()) {
+  public boolean equals(@Nullable Object object) {
+    if (object == null || this.getClass() != object.getClass()) {
       return false;
     }
     CloneGroup another = (CloneGroup) object;
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/index/ClonePart.java b/sonar-duplications/src/main/java/org/sonar/duplications/index/ClonePart.java
index 630f52c1350..0130f167197 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/index/ClonePart.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/index/ClonePart.java
@@ -21,6 +21,8 @@ package org.sonar.duplications.index;
 
 import org.sonar.duplications.CodeFragment;
 
+import javax.annotation.Nullable;
+
 public class ClonePart implements CodeFragment {
 
   private final String resourceId;
@@ -63,8 +65,8 @@ public class ClonePart implements CodeFragment {
   }
 
   @Override
-  public boolean equals(Object obj) {
-    if (this.getClass() == obj.getClass()) {
+  public boolean equals(@Nullable Object obj) {
+    if (obj != null && this.getClass() == obj.getClass()) {
       ClonePart another = (ClonePart) obj;
       return another.resourceId.equals(resourceId)
         && another.startLine == startLine