Merge "Mark return value of onBind() as @Nullable"

  public abstract class AttentionService extends android.app.Service {

    ctor public AttentionService();

    method public final android.os.IBinder onBind(android.content.Intent);

    method @Nullable public final android.os.IBinder onBind(@NonNull android.content.Intent);

    method public abstract void onCancelAttentionCheck(int);

    method public abstract void onCheckAttention(int, @NonNull android.service.attention.AttentionService.AttentionCallback);

    field public static final int ATTENTION_FAILURE_PREEMPTED = 2; // 0x2

import android.annotation.IntDef;

import android.annotation.NonNull;

import android.annotation.Nullable;

import android.annotation.SystemApi;

import android.app.Service;

import android.content.Intent;

        }

    };

    @Nullable

    @Override

    public final IBinder onBind(Intent intent) {

    public final IBinder onBind(@NonNull Intent intent) {

        if (SERVICE_INTERFACE.equals(intent.getAction())) {

            return mBinder;

        }