Check for mandatory Firebase Options. (#1140)

Author: ankitaj224

firebase-installations/src/main/java/com/google/firebase/installations/FirebaseInstallations.java

@@ -14,6 +14,7 @@
 
 package com.google.firebase.installations;
 
+import android.text.TextUtils;
 import androidx.annotation.GuardedBy;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -107,12 +108,22 @@ public class FirebaseInstallations implements FirebaseInstallationsApi {
   }
 
   /**
-   * Perform pre-condition checks to make sure {@link FirebaseOptions#getApiKey()} and {@link
-   * FirebaseOptions#getProjectId()} are not null.
+   * Perform pre-condition checks to make sure {@link FirebaseOptions#getApiKey()}, {@link
+   * FirebaseOptions#getApplicationId()} , and ({@link FirebaseOptions#getProjectId()} are not null
+   * or empty.
    */
   private void preConditionChecks() {
-    Preconditions.checkNotNull(firebaseApp.getOptions().getApiKey());
-    Preconditions.checkNotNull(firebaseApp.getOptions().getProjectId());
+    Preconditions.checkNotEmpty(getApplicationId());
+    Preconditions.checkNotEmpty(getProjectIdentifier());
+    Preconditions.checkNotEmpty(getApiKey());
+  }
+
+  /** Returns the Project Id or Project Number for the Firebase Project. */
+  @Nullable
+  String getProjectIdentifier() {
+    return TextUtils.isEmpty(firebaseApp.getOptions().getProjectId())
+        ? firebaseApp.getOptions().getGcmSenderId()
+        : firebaseApp.getOptions().getProjectId();
   }
 
   /**
@@ -144,6 +155,12 @@ String getApplicationId() {
     return firebaseApp.getOptions().getApplicationId();
   }
 
+  /** API key used to identify your app to Google servers. */
+  @Nullable
+  String getApiKey() {
+    return firebaseApp.getOptions().getApiKey();
+  }
+
   /** Returns the nick name of the {@link FirebaseApp} of this {@link FirebaseInstallations} */
   @VisibleForTesting
   String getName() {
@@ -193,7 +210,6 @@ public Task<InstallationTokenResult> getToken(@AuthTokenOption int authTokenOpti
   @NonNull
   @Override
   public Task<Void> delete() {
-    preConditionChecks();
     return Tasks.call(executor, this::deleteFirebaseInstallationId);
   }
 
@@ -374,9 +390,9 @@ private PersistedInstallationEntry registerFidWithServer(PersistedInstallationEn
 
     InstallationResponse response =
         serviceClient.createFirebaseInstallation(
-            /*apiKey= */ firebaseApp.getOptions().getApiKey(),
+            /*apiKey= */ getApiKey(),
             /*fid= */ prefs.getFirebaseInstallationId(),
-            /*projectID= */ firebaseApp.getOptions().getProjectId(),
+            /*projectID= */ getProjectIdentifier(),
             /*appId= */ getApplicationId(),
             /* migration-header= */ iidToken);
 
@@ -405,9 +421,9 @@ private PersistedInstallationEntry fetchAuthTokenFromServer(
       @NonNull PersistedInstallationEntry prefs) throws IOException {
     TokenResult tokenResult =
         serviceClient.generateAuthToken(
-            /*apiKey= */ firebaseApp.getOptions().getApiKey(),
+            /*apiKey= */ getApiKey(),
             /*fid= */ prefs.getFirebaseInstallationId(),
-            /*projectID= */ firebaseApp.getOptions().getProjectId(),
+            /*projectID= */ getProjectIdentifier(),
             /*refreshToken= */ prefs.getRefreshToken());
 
     switch (tokenResult.getResponseCode()) {
@@ -437,10 +453,10 @@ private Void deleteFirebaseInstallationId() throws FirebaseInstallationsExceptio
       // Call the FIS servers to delete this Firebase Installation Id.
       try {
         serviceClient.deleteFirebaseInstallation(
-            firebaseApp.getOptions().getApiKey(),
-            entry.getFirebaseInstallationId(),
-            firebaseApp.getOptions().getProjectId(),
-            entry.getRefreshToken());
+            /*apiKey= */ getApiKey(),
+            /*fid= */ entry.getFirebaseInstallationId(),
+            /*projectID= */ getProjectIdentifier(),
+            /*refreshToken= */ entry.getRefreshToken());
 
       } catch (FirebaseException exception) {
         throw new FirebaseInstallationsException(