Minimal MediaSessionCompat needed to get RemoteControlClient to appear

PlayerService.java

package com.example.remotecontrolclient;

import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.media.AudioManager;
import android.os.IBinder;
import android.support.v4.media.MediaMetadataCompat;
import android.support.v4.media.session.MediaSessionCompat;
import android.support.v4.media.session.PlaybackStateCompat;

public class PlayerService extends Service {
    private MediaSessionCompat mediaSession;

    @Override
    public void onCreate() {
        super.onCreate();
        ComponentName receiver = new ComponentName(getPackageName(), RemoteReceiver.class.getName());
        mediaSession = new MediaSessionCompat(this, "PlayerService", receiver, null);
        mediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS |
                MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);
        mediaSession.setPlaybackState(new PlaybackStateCompat.Builder()
                .setState(PlaybackStateCompat.STATE_PAUSED, 0, 0)
                .setActions(PlaybackStateCompat.ACTION_PLAY_PAUSE)
                .build());
        mediaSession.setMetadata(new MediaMetadataCompat.Builder()
                .putString(MediaMetadataCompat.METADATA_KEY_ARTIST, "Test Artist")
                .putString(MediaMetadataCompat.METADATA_KEY_ALBUM, "Test Album")
                .putString(MediaMetadataCompat.METADATA_KEY_TITLE, "Test Track Name")
                .putLong(MediaMetadataCompat.METADATA_KEY_DURATION, 10000)
                .putBitmap(MediaMetadataCompat.METADATA_KEY_ALBUM_ART,
                    BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
                .build());

        AudioManager audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        audioManager.requestAudioFocus(new AudioManager.OnAudioFocusChangeListener() {
            @Override
            public void onAudioFocusChange(int focusChange) {
                // Ignore
            }
        }, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);
        mediaSession.setActive(true);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (mediaSession.getController().getPlaybackState().getState() == PlaybackStateCompat.STATE_PLAYING) {
            mediaSession.setPlaybackState(new PlaybackStateCompat.Builder()
                    .setState(PlaybackStateCompat.STATE_PAUSED, 0, 0.0f)
                    .setActions(PlaybackStateCompat.ACTION_PLAY_PAUSE).build());
        } else {
            mediaSession.setPlaybackState(new PlaybackStateCompat.Builder()
                    .setState(PlaybackStateCompat.STATE_PLAYING, 0, 1.0f)
                    .setActions(PlaybackStateCompat.ACTION_PLAY_PAUSE).build());
        }
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mediaSession.release();
    }
}

RemoteReceiver.java

package com.example.remotecontrolclient;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.view.KeyEvent;

public class RemoteReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (Intent.ACTION_MEDIA_BUTTON.equals(intent.getAction())) {
            final KeyEvent event = intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT);

            if (event != null && event.getAction() == KeyEvent.ACTION_DOWN) {
                switch (event.getKeyCode()) {
                    case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
                        context.startService(new Intent(context, PlayerService.class));
                        break;
                }
            }
        }
    }
}

I am using this in an Activity and successfully receive the media buttons. However, in the lock screen nothing is displayed (even though the activity is in the background and with the mediaplayer active). Does the lockscreen functionality require a service?

How can I add SongList to the Queue of the session from activity? I can not see any kind of post regarding it.
I tried

mediaSessionCompat = MediaSessionCompat.fromMediaSession(mainActivity,mediaBrowserCompat.getSessionToken());
mediaSessionCompat.setQueue(queueList);

gives an error mediaSession is not a valid MediaSession object

I created a trivial working app project from this Gist at https://github.com/gregko/PlayerServiceSample. In the LogCat output one can see a message when a media button is pressed on a headset, when running on Android 5.x through 7.x. However it fails completely on Android 8 "Oreo", which final build Google just released. Would appreciate any hints on how to make this work under "Oreo", thanks!

i am getting same issue i have created one app in that one bluetooth device is bind with phone and according to event its working fine in below oreo but in that oreo not getting any action event if any one idea help me to solve out

I cannot change to "play" button, the button always show "pause", if i change to state to paused the playback screen not showing anything

This code not show anything
mediaSession.setPlaybackState(new PlaybackStateCompat.Builder()
.setState(PlaybackStateCompat.STATE_PAUSED, 0, 0.0f)
.setActions(PlaybackStateCompat.ACTION_PLAY_PAUSE).build());