code: public Group updateGroup(final String id, final GroupRequest groupRequest) throws UnauthorizedException, GeneralException {
          if (id == null) {
              throw new IllegalArgumentException("Group ID must be specified.");
          }
          String path = String.format("%s/%s", GROUPPATH, id);
          return messageBirdService.sendPayLoad("PATCH", path, groupRequest, Group.class);
      }
docs: Updates an existing group. You only need to supply the unique ID that
  was returned upon creation.