private @Nullable PsiJavaCodeReferenceElement getReferenceElement() {
    ASTNode ref = findChildByType(JavaElementType.JAVA_CODE_REFERENCE);
    if (ref == null) return null;
    return (PsiJavaCodeReferenceElement)SourceTreeToPsiMap.treeElementToPsi(ref);
  }
private @Nullable PsiJavaCodeReferenceElement getReferenceElement()