code: private static boolean shouldHasUniqueValues(List<Field> dataFields) {
          Set<String> dataValues = new HashSet<>();
          for (Field field : dataFields) {
              String value = field.getAnnotation(Plugin.Data.class).value();
              if (dataValues.contains(value)) {
                  return false;
              }
              dataValues.add(value);
          }
          return true;
      }
docs: Check that each given field has unique value in {@link Plugin.Data} annotation.