code: public static Maybe<List<String>> values(CacheConfigBean cacheConfigBean, String key) {
          return SingleRxXian
                  .call(CacheService.CACHE_SERVICE, "cacheMapValues", new JSONObject() {{
                      put("cacheConfig", cacheConfigBean);
                      put("key", key);
                  }})
                  .flatMapMaybe(unitResponse -> {
                      unitResponse.throwExceptionIfNotSuccess();
                      if (unitResponse.getData() == null)
                          return Maybe.empty();
                      else
                          return Maybe.just(Reflection.toTypedList(unitResponse.getData(), String.class));
                  });
      }
docs: retrieval all the values in the cache list
  
  @return the whole list if exists or null if the key does not exist.