docs: @Deprecated
      public Membership addGroupToProject(int projectId, int groupId, Collection<Role> roles) throws RedmineException {
          // "add user" and "add group" behave exactly the same way, actually. see
          // http://www.redmine.org/projects/redmine/wiki/Rest_Memberships#POST
          // http://www.redmine.org/issues/17904
          return new Membership(transport)
                  .setProject(new Project(transport).setId(projectId))
                  .setUserId(groupId)
                  .addRoles(roles)
                  .create();
      }