docs: public Iterable<BoxGroupMembership.Info> getAllMemberships(String ... fields) {
          final QueryStringBuilder builder = new QueryStringBuilder();
          if (fields.length > 0) {
              builder.appendParam("fields", fields);
          }
          return new Iterable<BoxGroupMembership.Info>() {
              public Iterator<BoxGroupMembership.Info> iterator() {
                  URL url = USER_MEMBERSHIPS_URL_TEMPLATE.buildWithQuery(
                          BoxUser.this.getAPI().getBaseURL(), builder.toString(), BoxUser.this.getID());
                  return new BoxGroupMembershipIterator(BoxUser.this.getAPI(), url);
              }
          };
      }