Class Conflict between two Firebase modules.

Start with the app-level Gradle dependencies shown in the issue and compare the firebase-admin and firebase-messaging artifacts with the linked Cloud Messaging tutorial. Determine whether both modules can coexist without the duplicate com.google.firebase.messaging package; done means a documented dependency setup resolves FirebaseMessaging and exposes the tutorial's sendMulticast API.

Environment

This is currently the dependencies used in my app-level Gradle build script

dependencies {
  implementation("androidx.appcompat:appcompat:1.6.1")
  implementation("com.google.android.material:material:1.10.0")
  implementation("androidx.constraintlayout:constraintlayout:2.1.4")
  implementation("androidx.navigation:navigation-fragment:2.7.5")
  implementation("androidx.navigation:navigation-ui:2.7.5")

  implementation("com.squareup.retrofit2:converter-gson:2.9.0")
  coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.0.4")

  implementation("com.google.firebase:firebase-admin:9.2.0")
  implementation("com.google.firebase:firebase-messaging:23.4.0")
}

Description

TL;DR: firebase-admin and firebase-messaging has the same classpath com.google.firebase.messaging.*, but their class's content is totally different.

Currently, I want to use both the module firebase-admin and firebase-messaging to learn about the feature Cloud Messaging, so I have installed my dependencies as above. The issue arose when I wanted to import the class FirebaseMessaging.

// Create a list containing up to 500 registration tokens.
// These registration tokens come from the client FCM SDKs.
List<String> registrationTokens = Arrays.asList(
    "YOUR_REGISTRATION_TOKEN_1",
    // ...
    "YOUR_REGISTRATION_TOKEN_n"
);

MulticastMessage message = MulticastMessage.builder()
    .putData("score", "850")
    .putData("time", "2:45")
    .addAllTokens(registrationTokens)
    .build();
BatchResponse response = FirebaseMessaging.getInstance().sendMulticast(message);
// See the BatchResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " messages were sent successfully");

While I was following [this tutorial] (https://firebase.google.com/docs/cloud-messaging/send-message#send-messages-to-multiple-devices) to build a send request to multiple devices, my IDE could not resolve the method sendMutlicast()

It turned out that while the imported class was com.google.firebase.messaging.FirebaseMessaging, the class was from the module firebase-messaging , which did not contain any of useful send method, rather than firebase-admin.

Is there anyway I can import the class FirebaseMessaging from firebase-admin and still keeping the two modules? I had switching the import order in Gradle file but still to no avail.

Thank you very much!