docs: public Member addMember(Object groupIdOrPath, Integer userId, Integer accessLevel, Date expiresAt) throws GitLabApiException {
  
          GitLabApiForm formData = new GitLabApiForm()
                  .withParam("user_id", userId, true)
                  .withParam("access_level", accessLevel, true)
                  .withParam("expires_at",  expiresAt, false);
          Response response = post(Response.Status.CREATED, formData, "groups", getGroupIdOrPath(groupIdOrPath), "members");
          return (response.readEntity(Member.class));
      }