appwrite/docs/examples/1.5.x/server-kotlin/java/messaging/update-f-c-m-provider.md

import io.appwrite.Client;
import io.appwrite.coroutines.CoroutineCallback;
import io.appwrite.services.Messaging;

Client client = new Client()
    .setEndpoint("https://<REGION>.cloud.appwrite.io/v1") // Your API Endpoint
    .setProject("5df5acd0d48c2") // Your project ID
    .setKey("919c2d18fb5d4...a2ae413da83346ad2"); // Your secret API key

Messaging messaging = new Messaging(client);

messaging.updateFCMProvider(
    "[PROVIDER_ID]", // providerId
    "[NAME]", // name (optional)
    false, // enabled (optional)
    mapOf( "a" to "b" ), // serviceAccountJSON (optional)
    new CoroutineCallback<>((result, error) -> {
        if (error != null) {
            error.printStackTrace();
            return;
        }

        System.out.println(result);
    })
);