code: public static TypeMirror getWildcardType(String type, String elementType, Elements elements,
                                             Types types) {
      TypeElement arrayList = elements.getTypeElement(type);
      TypeMirror elType = elements.getTypeElement(elementType).asType();
      return types.getDeclaredType(arrayList, types.getWildcardType(elType, null));
    }
docs: Get the wildcardType