@Override
 public void onInitialize(RefElement refElement) {
   if (refElement instanceof RefMethod) {
     final PsiElement element = refElement.getElement();
     if (!(element instanceof PsiMethod)) return;
     if (!PsiType.BOOLEAN.equals(((PsiMethod) element).getReturnType())) return;
     refElement.putUserData(ALWAYS_INVERTED, Boolean.TRUE); // initial mark boolean methods
   }
 }