docs: public static TypeMirror upperBound(Elements elements, TypeMirror type) {
      if (type.getKind() == TypeKind.WILDCARD) {
        WildcardType wildcard = (WildcardType) type;
        type = wildcard.getExtendsBound();
        if (type == null) {
          type = elements.getTypeElement(Object.class.getName()).asType();
        }
      }
      return type;
    }