我正在尝试使用firebase admin sdk创建应用程序，此管理应用程序将通过向firebase admin sdk subscription方法传递注册令牌列表来为设备订阅主题。
当我试图这样做，我得到的主题错误。有谁能告诉我为什么会出现这个错误，我应该把serviceaccountkey.json文件保存在哪里，这样它才可读。

这是我的密码

public class MainActivity extends AppCompatActivity {
String TOPIC="shop";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    FileInputStream serviceAccount;
    File serviceAccountFile = new File("./ServiceAccountKey.json");

    Boolean isFile =serviceAccountFile.isFile();
    Boolean canRead = serviceAccountFile.canRead();

    if (serviceAccountFile.isFile() && serviceAccountFile.canRead()) {

        {
            try {
                serviceAccount = new FileInputStream(serviceAccountFile);
                FirebaseOptions options = FirebaseOptions.builder().setCredentials(GoogleCredentials.fromStream(serviceAccount)).build();
                FirebaseApp.initializeApp(options);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    Firestore db = (Firestore) FirestoreClient.getFirestore().collection("USERS").document().get();

    List<String> registrationTokens = Arrays.asList(
        "TOKEN1", "TOKEN1"
    );

    TopicManagementResponse response;

    {
        try {
            response = FirebaseMessaging.getInstance().subscribeToTopic(
                    registrationTokens, TOPIC);
            System.out.println(response.getSuccessCount() + " tokens were subscribed successfully");
        } catch (FirebaseMessagingException e) {
            e.printStackTrace();
        }
    }

}

} }
! 我的项目结构文件的当前位置
我的应用程序版本.gradle

apply plugin: 'com.android.application'

android{compilesdkversion 29 buildtoolsversion“30.0.0”

defaultConfig {
    applicationId "com.example.firebaseadminsdk"
    minSdkVersion 22
    targetSdkVersion 29
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
    customDebugType {
        debuggable true
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}

packagingOptions {
    exclude 'META-INF/INDEX.LIST'
    exclude 'META-INF/DEPENDENCIES'
    exclude 'META-INF/native-image/io.netty/transport/native-image.properties'
    exclude 'META-INF/native-image/io.netty/transport/reflection-config.json'
    exclude 'META-INF/native-image/io.netty/codec-http/native-image.properties'
    exclude 'META-INF/native-image/io.netty/buffer/native-image.properties'
    exclude 'META-INF/native-image/io.netty/handler/native-image.properties'
    exclude 'META-INF/native-image/io.netty/common/native-image.properties'
    exclude 'META-INF/io.netty.versions.properties'

}

}

dependencies {
implementation fileTree(dir: "libs", include: ["*.jar"])
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
testImplementation 'junit:junit:4.13.1'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
implementation 'com.google.firebase:firebase-admin:7.0.1'

}