code: public static Single<Boolean> exists(CacheConfigBean cacheConfigBean, String cacheKey) {
          return SingleRxXian.call(CacheService.CACHE_SERVICE, "cacheListExists", new JSONObject() {{
              put("cacheConfig", cacheConfigBean);
              put("key", cacheKey);
          }}).map(UnitResponse::dataToBoolean);
      }
docs: check whether the list exists
  
  @param cacheConfigBean the cache data source.
  @param cacheKey        the cache key
  @return true if exists, other wise false