public boolean pushSessionNotification(DeviceType deviceType, String serverId) {
        UserSession userSession = deviceTypeToSession.get(deviceType);
        if (userSession == null) {
            return false;
        }
        try {
            userSession
                    .sendNotification(ClientMessageEncoder.encodeUserSessionNotification(System
                            .currentTimeMillis(), Integer.toString(userSession.getId()), serverId))
                    .subscribe(null,
                            t -> LOGGER.error(
                                    "Failed to send the session notification to the user session: "
                                            + userSession,
                                    t));
            return true;
        } catch (Exception e) {
            LOGGER.error("Failed to send the session notification to the user session: "
                    + userSession, e);
            return false;
        }
    }
@return true if the notification is sent
turms-gateway/src/main/java/im/turms/gateway/domain/session/manager/UserSessionsManager.java