equals() in the object hierarchy must check for class

platform/editor-ui-api/src/com/intellij/ide/util/treeView/AbstractTreeNode.java

@@ -120,6 +120,8 @@ public abstract class AbstractTreeNode<T> extends PresentableNodeDescriptor<Abst
   }
 
   public boolean equals(Object object) {
+    if (object == this) return true;
+    if (object == null || !object.getClass().equals(getClass())) return false;
     // we should not change this behaviour if value is set to null
     return object instanceof AbstractTreeNode && Comparing.equal(myValue, ((AbstractTreeNode)object).myValue);
   }

plugins/properties/src/com/intellij/lang/properties/projectView/CustomResourceBundlePropertiesFileNode.java

@@ -31,14 +31,6 @@ public class CustomResourceBundlePropertiesFileNode extends PsiFileNode implemen
     data.setLocationString(PropertiesBundle.message("project.view.resource.bundle.tree.node.text", getResourceBundle().getBaseName()));
   }
 
-  @Override
-  public boolean equals(Object object) {
-    if (!(object instanceof CustomResourceBundlePropertiesFileNode)) {
-      return false;
-    }
-    return Comparing.equal(getValue(), ((CustomResourceBundlePropertiesFileNode)object).getValue());
-  }
-
   @NotNull
   @Override
   public ResourceBundle getResourceBundle() {