Add lint check that detects UI thread continuations.

appcheck/firebase-appcheck-debug/src/main/java/com/google/firebase/appcheck/debug/internal/DebugAppCheckProvider.java

@@ -21,14 +21,12 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
-import com.google.android.gms.tasks.Continuation;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.FirebaseApp;
 import com.google.firebase.appcheck.AppCheckProvider;
 import com.google.firebase.appcheck.AppCheckToken;
-import com.google.firebase.appcheck.internal.AppCheckTokenResponse;
 import com.google.firebase.appcheck.internal.DefaultAppCheckToken;
 import com.google.firebase.appcheck.internal.NetworkClient;
 import com.google.firebase.appcheck.internal.RetryManager;
@@ -95,35 +93,31 @@ static Task<String> determineDebugSecret(
     return taskCompletionSource.getTask();
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   @Override
   public Task<AppCheckToken> getToken() {
     return debugSecretTask
         .continueWithTask(
-            new Continuation<String, Task<AppCheckTokenResponse>>() {
-              @Override
-              public Task<AppCheckTokenResponse> then(@NonNull Task<String> task) throws Exception {
-                ExchangeDebugTokenRequest request = new ExchangeDebugTokenRequest(task.getResult());
-                return Tasks.call(
-                    backgroundExecutor,
-                    () ->
-                        networkClient.exchangeAttestationForAppCheckToken(
-                            request.toJsonString().getBytes(UTF_8),
-                            NetworkClient.DEBUG,
-                            retryManager));
-              }
+            task -> {
+              ExchangeDebugTokenRequest request = new ExchangeDebugTokenRequest(task.getResult());
+              return Tasks.call(
+                  backgroundExecutor,
+                  () ->
+                      networkClient.exchangeAttestationForAppCheckToken(
+                          request.toJsonString().getBytes(UTF_8),
+                          NetworkClient.DEBUG,
+                          retryManager));
             })
         .continueWithTask(
-            new Continuation<AppCheckTokenResponse, Task<AppCheckToken>>() {
-              @Override
-              public Task<AppCheckToken> then(@NonNull Task<AppCheckTokenResponse> task) {
-                if (task.isSuccessful()) {
-                  return Tasks.forResult(
-                      DefaultAppCheckToken.constructFromAppCheckTokenResponse(task.getResult()));
-                }
-                // TODO: Surface more error details.
-                return Tasks.forException(task.getException());
+            task -> {
+              if (task.isSuccessful()) {
+                return Tasks.forResult(
+                    DefaultAppCheckToken.constructFromAppCheckTokenResponse(task.getResult()));
               }
+              // TODO: Surface more error details.
+              return Tasks.forException(task.getException());
             });
   }
 }

appcheck/firebase-appcheck-playintegrity/src/main/java/com/google/firebase/appcheck/playintegrity/internal/PlayIntegrityAppCheckProvider.java

@@ -67,6 +67,8 @@ public PlayIntegrityAppCheckProvider(@NonNull FirebaseApp firebaseApp) {
     this.retryManager = retryManager;
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   @Override
   public Task<AppCheckToken> getToken() {
@@ -90,6 +92,8 @@ public Task<AppCheckToken> getToken() {
             });
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   private Task<IntegrityTokenResponse> getPlayIntegrityAttestation() {
     GeneratePlayIntegrityChallengeRequest generateChallengeRequest =

appcheck/firebase-appcheck-safetynet/src/main/java/com/google/firebase/appcheck/safetynet/internal/SafetyNetAppCheckProvider.java

@@ -26,7 +26,6 @@
 import com.google.android.gms.safetynet.SafetyNet;
 import com.google.android.gms.safetynet.SafetyNetApi;
 import com.google.android.gms.safetynet.SafetyNetClient;
-import com.google.android.gms.tasks.Continuation;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.android.gms.tasks.Tasks;
@@ -140,39 +139,35 @@ Task<SafetyNetClient> getSafetyNetClientTask() {
     return safetyNetClientTask;
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   @Override
   public Task<AppCheckToken> getToken() {
     return safetyNetClientTask
         .continueWithTask(
-            new Continuation<SafetyNetClient, Task<SafetyNetApi.AttestationResponse>>() {
-              @Override
-              public Task<SafetyNetApi.AttestationResponse> then(
-                  @NonNull Task<SafetyNetClient> task) {
-                if (task.isSuccessful()) {
-                  return task.getResult().attest(NONCE.getBytes(), apiKey);
-                }
-                return Tasks.forException(task.getException());
+            task -> {
+              if (task.isSuccessful()) {
+                return task.getResult().attest(NONCE.getBytes(), apiKey);
               }
+              return Tasks.forException(task.getException());
             })
         .continueWithTask(
-            new Continuation<SafetyNetApi.AttestationResponse, Task<AppCheckToken>>() {
-              @Override
-              public Task<AppCheckToken> then(
-                  @NonNull Task<SafetyNetApi.AttestationResponse> task) {
-                if (!task.isSuccessful()) {
-                  // Proxies errors to the client directly; need to wrap to get the
-                  // types right.
-                  // TODO: more specific error mapping to help clients debug more
-                  //       easily.
-                  return Tasks.forException(task.getException());
-                } else {
-                  return exchangeSafetyNetAttestationResponseForToken(task.getResult());
-                }
+            task -> {
+              if (!task.isSuccessful()) {
+                // Proxies errors to the client directly; need to wrap to get the
+                // types right.
+                // TODO: more specific error mapping to help clients debug more
+                //       easily.
+                return Tasks.forException(task.getException());
+              } else {
+                return exchangeSafetyNetAttestationResponseForToken(task.getResult());
               }
             });
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   Task<AppCheckToken> exchangeSafetyNetAttestationResponseForToken(
       @NonNull SafetyNetApi.AttestationResponse attestationResponse) {
@@ -191,16 +186,13 @@ Task<AppCheckToken> exchangeSafetyNetAttestationResponseForToken(
                     NetworkClient.SAFETY_NET,
                     retryManager));
     return networkTask.continueWithTask(
-        new Continuation<AppCheckTokenResponse, Task<AppCheckToken>>() {
-          @Override
-          public Task<AppCheckToken> then(@NonNull Task<AppCheckTokenResponse> task) {
-            if (task.isSuccessful()) {
-              return Tasks.forResult(
-                  DefaultAppCheckToken.constructFromAppCheckTokenResponse(task.getResult()));
-            }
-            // TODO: Surface more error details.
-            return Tasks.forException(task.getException());
+        task -> {
+          if (task.isSuccessful()) {
+            return Tasks.forResult(
+                DefaultAppCheckToken.constructFromAppCheckTokenResponse(task.getResult()));
           }
+          // TODO: Surface more error details.
+          return Tasks.forException(task.getException());
         });
   }
 }

appcheck/firebase-appcheck/src/main/java/com/google/firebase/appcheck/internal/DefaultFirebaseAppCheck.java

@@ -20,7 +20,6 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
-import com.google.android.gms.tasks.Continuation;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.android.gms.tasks.Tasks;
@@ -176,6 +175,8 @@ public void removeAppCheckListener(@NonNull AppCheckListener listener) {
         appCheckTokenListenerList.size() + appCheckListenerList.size());
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   @Override
   public Task<AppCheckTokenResult> getToken(boolean forceRefresh) {
@@ -210,6 +211,8 @@ public Task<AppCheckTokenResult> getToken(boolean forceRefresh) {
         });
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   @Override
   public Task<AppCheckToken> getAppCheckToken(boolean forceRefresh) {
@@ -226,27 +229,26 @@ public Task<AppCheckToken> getAppCheckToken(boolean forceRefresh) {
   }
 
   /** Fetches an {@link AppCheckToken} via the installed {@link AppCheckProvider}. */
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   Task<AppCheckToken> fetchTokenFromProvider() {
     return appCheckProvider
         .getToken()
         .continueWithTask(
-            new Continuation<AppCheckToken, Task<AppCheckToken>>() {
-              @Override
-              public Task<AppCheckToken> then(@NonNull Task<AppCheckToken> task) {
-                if (task.isSuccessful()) {
-                  AppCheckToken token = task.getResult();
-                  updateStoredToken(token);
-                  for (AppCheckListener listener : appCheckListenerList) {
-                    listener.onAppCheckTokenChanged(token);
-                  }
-                  AppCheckTokenResult tokenResult =
-                      DefaultAppCheckTokenResult.constructFromAppCheckToken(token);
-                  for (AppCheckTokenListener listener : appCheckTokenListenerList) {
-                    listener.onAppCheckTokenChanged(tokenResult);
-                  }
+            task -> {
+              if (task.isSuccessful()) {
+                AppCheckToken token = task.getResult();
+                updateStoredToken(token);
+                for (AppCheckListener listener : appCheckListenerList) {
+                  listener.onAppCheckTokenChanged(token);
+                }
+                AppCheckTokenResult tokenResult =
+                    DefaultAppCheckTokenResult.constructFromAppCheckToken(token);
+                for (AppCheckTokenListener listener : appCheckTokenListenerList) {
+                  listener.onAppCheckTokenChanged(tokenResult);
                 }
-                return task;
               }
+              return task;
             });
   }
 

appcheck/firebase-appcheck/src/main/java/com/google/firebase/appcheck/internal/DefaultTokenRefresher.java

@@ -21,7 +21,6 @@
 import android.annotation.SuppressLint;
 import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
-import com.google.android.gms.tasks.OnFailureListener;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
@@ -93,16 +92,12 @@ private long getNextRefreshMillis() {
     }
   }
 
+  // TODO(b/261013814): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   private void onRefresh() {
     firebaseAppCheck
         .fetchTokenFromProvider()
-        .addOnFailureListener(
-            new OnFailureListener() {
-              @Override
-              public void onFailure(@NonNull Exception e) {
-                scheduleRefreshAfterFailure();
-              }
-            });
+        .addOnFailureListener(e -> scheduleRefreshAfterFailure());
   }
 
   /** Cancels the in-flight scheduled refresh. */

firebase-appdistribution-api/src/main/java/com/google/firebase/appdistribution/internal/FirebaseAppDistributionStub.java

@@ -14,6 +14,7 @@
 
 package com.google.firebase.appdistribution.internal;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -38,6 +39,8 @@
  * Tasks}/{@link UpdateTask UpdateTasks} with {@link
  * FirebaseAppDistributionException.Status#NOT_IMPLEMENTED}.
  */
+// TODO(b/261013680): Use an explicit executor in continuations.
+@SuppressLint("TaskMainThread")
 public class FirebaseAppDistributionStub implements FirebaseAppDistribution {
   @NonNull
   @Override

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/AabUpdater.java

@@ -53,7 +53,7 @@ class AabUpdater {
   @GuardedBy("updateAabLock")
   private boolean hasBeenSentToPlayForCurrentTask = false;
 
-  // TODO(b/258264924): Migrate to go/firebase-android-executors
+  // TODO(b/261014422): Migrate to go/firebase-android-executors
   @SuppressLint("ThreadPoolCreation")
   AabUpdater() {
     this(

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/ApkUpdater.java

@@ -63,7 +63,7 @@ class ApkUpdater {
 
   private final Object updateTaskLock = new Object();
 
-  // TODO(b/258264924): Migrate to go/firebase-android-executors
+  // TODO(b/261014422): Migrate to go/firebase-android-executors
   @SuppressLint("ThreadPoolCreation")
   public ApkUpdater(@NonNull FirebaseApp firebaseApp, @NonNull ApkInstaller apkInstaller) {
     this(

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/FirebaseAppDistributionImpl.java

@@ -21,6 +21,7 @@
 import static com.google.firebase.appdistribution.impl.TaskUtils.safeSetTaskException;
 import static com.google.firebase.appdistribution.impl.TaskUtils.safeSetTaskResult;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.Context;
@@ -101,6 +102,8 @@ class FirebaseAppDistributionImpl implements FirebaseAppDistribution {
 
   @Override
   @NonNull
+  // TODO(b/261014422): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   public UpdateTask updateIfNewReleaseAvailable() {
     synchronized (updateIfNewReleaseTaskLock) {
       if (updateIfNewReleaseAvailableIsTaskInProgress()) {
@@ -111,7 +114,6 @@ public UpdateTask updateIfNewReleaseAvailable() {
       remakeUpdateConfirmationDialog = false;
       dialogHostActivity = null;
     }
-
     lifecycleNotifier
         .applyToForegroundActivityTask(this::showSignInConfirmationDialog)
         .onSuccessTask(unused -> signInTester())
@@ -219,6 +221,8 @@ public void signOutTester() {
 
   @Override
   @NonNull
+  // TODO(b/261014422): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   public synchronized Task<AppDistributionRelease> checkForNewRelease() {
     if (cachedCheckForNewReleaseTask != null && !cachedCheckForNewReleaseTask.isComplete()) {
       LogWrapper.getInstance().v("Response in progress");

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/FirebaseAppDistributionTesterApiClient.java

@@ -65,7 +65,7 @@ private interface FidDependentJob<TResult> {
   private final Provider<FirebaseInstallationsApi> firebaseInstallationsApiProvider;
   private final TesterApiHttpClient testerApiHttpClient;
 
-  // TODO(b/258264924): Migrate to go/firebase-android-executors
+  // TODO(b/261014422): Migrate to go/firebase-android-executors
   @SuppressLint("ThreadPoolCreation")
   private final Executor taskExecutor = Executors.newSingleThreadExecutor();
 

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/NewReleaseFetcher.java

@@ -16,6 +16,7 @@
 
 import static com.google.firebase.appdistribution.impl.PackageInfoUtils.getPackageInfo;
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
@@ -48,6 +49,8 @@ class NewReleaseFetcher {
     this.releaseIdentifier = releaseIdentifier;
   }
 
+  // TODO(b/261014422): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   public synchronized Task<AppDistributionReleaseInternal> checkForNewRelease() {
     if (cachedCheckForNewRelease != null && !cachedCheckForNewRelease.isComplete()) {

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/TesterSignInManager.java

@@ -18,6 +18,7 @@
 import static com.google.firebase.appdistribution.impl.TaskUtils.safeSetTaskException;
 import static com.google.firebase.appdistribution.impl.TaskUtils.safeSetTaskResult;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
@@ -113,6 +114,8 @@ void onActivityResumed(Activity activity) {
     }
   }
 
+  // TODO(b/261014422): Use an explicit executor in continuations.
+  @SuppressLint("TaskMainThread")
   @NonNull
   public Task<Void> signInTester() {
     if (signInStorage.getSignInStatus()) {

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/UpdateTaskImpl.java

@@ -14,6 +14,7 @@
 
 package com.google.firebase.appdistribution.impl;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import androidx.annotation.GuardedBy;
 import androidx.annotation.NonNull;
@@ -34,6 +35,8 @@
 import java.util.concurrent.Executor;
 
 /** Implementation of UpdateTask, the return type of updateApp. */
+// TODO(b/261013814): Use an explicit executor in continuations.
+@SuppressLint("TaskMainThread")
 class UpdateTaskImpl extends UpdateTask {
   @Nullable
   @GuardedBy("lock")