使用Firebase时，GoogleSignIn被标记为内部，不应从应用程序访问

我正在尝试在我的Android应用中检索已登录用户的联系电子邮件的列表。从此处的教程开始，以下行：

mGoogleSignInClient = GoogleSignIn.getClient(this, gso);

导致Android Studio错误“ GoogleSignIn被标记为内部，不应从应用程序访问”。

该项目可以编译，但是当我尝试登录时，logcat输出：

W/GooglePlayServicesUtil: Google Play services out of date.  Requires 12210000 but found 11947470

我的app/gradle.build包含：

dependencies {
    ...
    implementation 'com.google.android.gms:play-services-auth:12.0.0'
    implementation 'com.google.firebase:firebase-core:12.0.0'
    implementation 'com.google.firebase:firebase-firestore:12.0.0'
}
apply plugin: 'com.google.gms.google-services'

当我注释掉Firebase时：

dependencies {
    ...
    implementation 'com.google.android.gms:play-services-auth:12.0.0'
    //implementation 'com.google.firebase:firebase-core:12.0.0'
    //implementation 'com.google.firebase:firebase-firestore:12.0.0'
}
//apply plugin: 'com.google.gms.google-services'

我没有收到错误并成功登录。

我想将Firestorm集成到我的应用程序中，是否需要重新设计登录过程？如果是这样，怎么办？

要复制，这是我的MainActivity。编译Firebase后，Log.w调用输出signInResult:failed code=12500：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    static final int RC_SIGN_IN = 1000;
    GoogleSignInClient mGoogleSignInClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestEmail()
                .build();
        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
        findViewById(R.id.google_sign_in_button).setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        startActivityForResult(mGoogleSignInClient.getSignInIntent(), RC_SIGN_IN);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == RC_SIGN_IN) {
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            handleSignInResult(task);
        }
    }

    private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
        try {
            GoogleSignInAccount account = completedTask.getResult(ApiException.class);
        } catch (ApiException e) {
            Log.w("signInResult:failed code=" + e.getStatusCode());
        }
    }
}

和我的布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.XXX.MainActivity">
    <com.google.android.gms.common.SignInButton
        android:id="@+id/google_sign_in_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>
</android.support.constraint.ConstraintLayout>