[google-appengine] Initializing Firebase Admin in App Engine standard Java

[Zeyad Almajed]

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<https://stackoverflow.com/questions/48045808/initializing-firebase-admin-in-app-engine-standard-java#>
2

I'm trying to use Firebase Auth in App engine standard Java to verify 
tokens from Android.

However, when I try to initialize Firebase admin, I get an Exception.

here is the exception:

java.lang.NoSuchMethodError: 
com.google.common.base.Preconditions.checkState(ZLjava/lang/String;Ljava/lang/Object;)V
at com.google.firebase.FirebaseApp.checkNotDeleted (FirebaseApp.java:352)
at com.google.firebase.FirebaseApp.getOptions (FirebaseApp.java:267)
at com.google.firebase.FirebaseApp$TokenRefresher.<init> (FirebaseApp.java:434)
at com.google.firebase.FirebaseApp$TokenRefresher$Factory.create 
(FirebaseApp.java:535)
at com.google.firebase.FirebaseApp.<init> (FirebaseApp.java:113)
at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:201)
at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:188)
at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:175)

Most likely, because of conflict in Guava versions

here is my gradle:

dependencies {
    appengineSdk 'com.google.appengine:appengine-java-sdk:1.9.60'
    compile 'com.google.appengine.tools:appengine-gcs-client:0.7'
    compile ('com.google.firebase:firebase-admin:5.7.0') {
        exclude group: 'com.google.guava'
    }
    compile 'com.google.guava:guava:23.0'
    compile 'javax.servlet:servlet-api:2.5'}

Here is the code:

InputStream in = filterConfig.getServletContext()
            .getResourceAsStream("/WEB-INF/PRIVATE_KEY_JSON.json");
FirebaseOptions options = null;try {
     options = new FirebaseOptions.Builder()
            .setCredentials(GoogleCredentials.fromStream(in))
            .build();} catch (IOException e) {
    e.printStackTrace();}FirebaseApp.initializeApp(options);

java <https://stackoverflow.com/questions/tagged/java> google-app-engine 
<https://stackoverflow.com/questions/tagged/google-app-engine> 
firebase-admin <https://stackoverflow.com/questions/tagged/firebase-admin>

https://stackoverflow.com/questions/48045808/initializing-firebase-admin-in-app-engine-standard-java

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