code: public LoginWithSignResult loginWithSign(LoginWithSignRequest request) {
  
  		ObjectNode body = JsonNodeFactory.instance.objectNode()
  				.put("serviceId", request.getServiceId())
  				.put("userId", request.getUserId())
  				.put("keyName", request.getKeyName())
  				.put("sign", request.getSign());
  
  		HttpPost post = createHttpPost(
  				Gs2Constant.ENDPOINT_HOST + "/login/signed",
  				credential,
  				ENDPOINT,
  				LoginWithSignRequest.Constant.MODULE,
  				LoginWithSignRequest.Constant.FUNCTION,
  				body.toString());
          if(request.getRequestId() != null) {
              post.setHeader("X-GS2-REQUEST-ID", request.getRequestId());
          }
  
  
  		return doRequest(post, LoginWithSignResult.class);
  
  	}
docs: GS2-Accountの認証署名付きログイン処理を実行します<br>
  <br>
  
  @param request リクエストパラメータ
  
  @return 結果