private static void moveExtendsToImplements(PsiClass anInterface) {
    final PsiReferenceList extendsList = anInterface.getExtendsList();
    final PsiReferenceList implementsList = anInterface.getImplementsList();
    assert extendsList != null;
    final PsiJavaCodeReferenceElement[] extendsRefElements = extendsList.getReferenceElements();
    for (PsiJavaCodeReferenceElement referenceElement : extendsRefElements) {
      assert implementsList != null;
      final PsiElement resolved = referenceElement.resolve();
      if (resolved instanceof PsiClass && ((PsiClass)resolved).isInterface()) {
        implementsList.add(referenceElement);
        referenceElement.delete();
      }
    }
  }
private static void moveExtendsToImplements(PsiClass anInterface)