问java:找不到com.google.auth.Credentials，无法访问com.google.auth.Credentials类文件

EN

Error:(22, 36) java: cannot access com.google.auth.Credentials
class file for com.google.auth.Credentials not found

import com.google.auth.oauth2.GoogleCredentials;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import com.google.firebase.database.*;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

class Database{

private FirebaseDatabase firebaseDatabase;

Database(){

    InputStream serviceAccount = Database.class.getResourceAsStream("reading-incentive-firebase-adminsdk-n556s-1b742e4b58.json");

    FirebaseOptions options;
    try {
        options = new FirebaseOptions.Builder()
                .setCredentials( GoogleCredentials.fromStream(serviceAccount))
                .setDatabaseUrl("https://reading-incentive.firebaseio.com")
                .build();
        FirebaseApp.initializeApp(options);
    } catch (IOException e) {
        e.printStackTrace();
        System.out.println("Error loading database");
    }

    firebaseDatabase = FirebaseDatabase.getInstance();

}

}

group 'src'
version '1.0-SNAPSHOT'

apply plugin: 'java'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    implementation 'com.google.firebase:firebase-admin:6.5.0'
}