How to get Call backs from Jitsi Meet activity

I am extending JitsiMeetActivity.
My interest in in callback like onConferenceTerminated , onConferenceJoined etc.
Also how can we get informed if any new participant joins the conference?

     serverURL = try {
            } catch (e: MalformedURLException) {
                throw RuntimeException("Invalid server URL!")
            userInfo = JitsiMeetUserInfo()
            userInfo.displayName = userStorage.UserX_name
            if (null != userStorage.UserX_image && !userStorage.UserX_image.isNullOrBlank()) {
                userInfo.avatar = URL(userStorage.UserX_image)
            defaultOptions = JitsiMeetConferenceOptions.Builder()
                    .setFeatureFlag("call-integration.enabled", false)

  JitsiMeetActivity.launch(this@VideoClassRoom, options)

I am Using this Code with extending JitsiMeetActivity.