code: public UserInfoResponse callUserInfo(String accessToken)
      {
          // Create a request for Authlete's /api/auth/userinfo API.
          UserInfoRequest request = new UserInfoRequest()
              .setToken(accessToken);
  
          try
          {
              // Call Authlete's /api/auth/userinfo API.
              return mApi.userinfo(request);
          }
          catch (AuthleteApiException e)
          {
              // The API call failed.
              throw apiFailure("/api/auth/userinfo", e);
          }
      }
docs: Call Authlete's {@code /api/auth/userinfo} API.