code: public static Iterable<BoxRetentionPolicy.Info> getAll(final BoxAPIConnection api, String ... fields) {
          return getAll(null, null, null, DEFAULT_LIMIT, api, fields);
      }
docs: Returns all the retention policies.
  @param api the API connection to be used by the resource.
  @param fields the fields to retrieve.
  @return an iterable with all the retention policies.