@Contract("null,_ -> false")
  public static boolean isImmutable(@Nullable PsiType type, boolean checkDocComment) {
    if (TypeConversionUtil.isPrimitiveAndNotNull(type)) {
      return true;
    }
    final PsiClass aClass = PsiUtil.resolveClassInClassTypeOnly(type);
    if (aClass == null) {
      return false;
    }
    return isImmutableClass(aClass, checkDocComment);
  }
@Contract("null,_ -> false")
  public static boolean isImmutable(@Nullable PsiType type, boolean checkDocComment)