private static void moveImplementsToExtends(PsiClass anInterface) {
      final PsiReferenceList extendsList = anInterface.getExtendsList();
      if (extendsList == null) {
        return;
      }
      final PsiReferenceList implementsList = anInterface.getImplementsList();
      if (implementsList == null) {
        return;
      }
      final PsiJavaCodeReferenceElement[] referenceElements = implementsList.getReferenceElements();
      for (final PsiJavaCodeReferenceElement referenceElement : referenceElements) {
        extendsList.add(referenceElement);
        referenceElement.delete();
      }
    }
private static void moveImplementsToExtends(PsiClass anInterface)