private static boolean findAndRemoveReturnCheck(Statement stat, StructMethod mt) {

    boolean is_notnull_check = false;

    // method annotation, refers to the return value
    StructAnnotationAttribute attr = mt.getAttribute(StructGeneralAttribute.ATTRIBUTE_RUNTIME_INVISIBLE_ANNOTATIONS);
    if (attr != null) {
      List<AnnotationExprent> annotations = attr.getAnnotations();

      for (AnnotationExprent ann : annotations) {
        if (ann.getClassName().equals("org/jetbrains/annotations/NotNull")) {
          is_notnull_check = true;
          break;
        }
      }
    }

    return is_notnull_check && removeReturnCheck(stat, mt);
  }
private static boolean findAndRemoveReturnCheck(Statement stat, StructMethod mt)