Java-app-sdk onActivation not happens

[almaz]

Hi!
I am using end devices + gateway + TTN server + java-app-sdk.
onMessage event works well - I can detect all uplink messages from end devices sent to server. But no onActivation event happens on adding new end device to TTN and passing join procedure. Here is code:
Client client = new Client(region, appId, accessKey);

        client.onError((Throwable _error) -> log.warning("error: " + _error.getMessage()));

        client.onConnected((Connection _client) -> log.info("connected !"));

        client.onActivation((String devId, ActivationMessage data) -> {
            log.info("\r\n====================================\r\n"
                    + "AppEui: " + data.getAppEui()
                    + "DevEui: " + data.getDevEui());
    });
        
        client.onMessage((String devId, DataMessage data) -> {
            log.info("\r\n###############################"
                        + "\r\nMessage from device " + devId + " with: "
                        + "\r\nAppId: " +  ((UplinkMessage)data).getAppId()
                        + "\r\nDevId: " + ((UplinkMessage)data).getDevId()
                        + "\r\nCounter: " + ((UplinkMessage)data).getCounter()
                        + "\r\nHWserial: " + ((UplinkMessage)data).getHardwareSerial()
                        + "\r\nPort: " + ((UplinkMessage)data).getPort()
                        + "\r\nDataRaw: " + bytesToHex(((UplinkMessage)data).getPayloadRaw())
                        + "\r\nGateway: " + ((UplinkMessage)data).getMetadata().getGateways().get(0).getId());

            DownlinkMessage responce = new DownlinkMessage(((UplinkMessage)data).getPort(), "hello");
            log.info("Sending");
            try {
                client.send(devId, responce);
            } catch (Exception e) {
                log.warning("Responce failed: " + e.getMessage());
            }
        });

        client.start();

Here is sequence while trying to catch activation event:

1. gateway stopped
2. end device deleted from application on TTN server
3. java-app-sdk started
4. end device added to applicatioin on TTN server
5. gateway started
6. end device started

Join procedure passes succesfully (as well as activation on TTN):

but only uplink messages catched using onMessage handler: