@Nullable
  private static PsiClass extractClass(PsiElement element) {
    if (element instanceof PsiReferenceExpression) {
      PsiElement target = ((PsiReferenceExpression)element).resolve();
      if (target instanceof PsiClass) {
        return (PsiClass)target;
      }
    }
    if (element instanceof PsiExpression) {
      PsiClass psiClass = PsiUtil.resolveClassInClassTypeOnly(((PsiExpression)element).getType());
      return psiClass instanceof PsiAnonymousClass ? psiClass.getSuperClass() : psiClass;
    }
    return null;
  }
@Nullable
  private static PsiClass extractClass(PsiElement element)