code: public static Single<Boolean> addAll(String cacheKey, List list) {
          return addAll(CacheService.CACHE_CONFIG_BEAN, cacheKey, list);
      }
docs: Add a list of elements to the end of the cached list.
  
  @param cacheKey the key for the cached list.
  @param list     the list of elements to be added.
  @return true on success, false on failure.