fix: Remove the copy of Function interface, and instead make use of the Function interface now offered as part of minimum API version.

Author: tom-andersen

firebase-firestore/src/androidTest/java/com/google/firebase/firestore/AccessHelper.java

@@ -21,7 +21,7 @@
 import com.google.firebase.firestore.core.ComponentProvider;
 import com.google.firebase.firestore.model.DatabaseId;
 import com.google.firebase.firestore.util.AsyncQueue;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 
 /** Gives access to package private methods in integration tests. */
 public final class AccessHelper {

firebase-firestore/src/main/java/com/google/firebase/firestore/FirebaseFirestore.java

@@ -27,6 +27,7 @@
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.android.gms.tasks.Tasks;
+import com.google.common.base.Function;
 import com.google.firebase.FirebaseApp;
 import com.google.firebase.annotations.PreviewApi;
 import com.google.firebase.appcheck.interop.InteropAppCheckTokenProvider;
@@ -51,7 +52,6 @@
 import com.google.firebase.firestore.util.AsyncQueue;
 import com.google.firebase.firestore.util.ByteBufferInputStream;
 import com.google.firebase.firestore.util.Executors;
-import com.google.firebase.firestore.util.Function;
 import com.google.firebase.firestore.util.Logger;
 import com.google.firebase.firestore.util.Logger.Level;
 import com.google.firebase.firestore.util.Preconditions;

firebase-firestore/src/main/java/com/google/firebase/firestore/FirestoreClientProvider.java

@@ -18,9 +18,9 @@
 import androidx.annotation.VisibleForTesting;
 import androidx.core.util.Consumer;
 import com.google.android.gms.tasks.Task;
+import com.google.common.base.Function;
 import com.google.firebase.firestore.core.FirestoreClient;
 import com.google.firebase.firestore.util.AsyncQueue;
-import com.google.firebase.firestore.util.Function;
 import java.util.concurrent.Executor;
 
 /**

firebase-firestore/src/main/java/com/google/firebase/firestore/core/CompositeFilter.java

@@ -17,7 +17,7 @@
 import android.text.TextUtils;
 import androidx.annotation.Nullable;
 import com.google.firebase.firestore.model.Document;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;

firebase-firestore/src/main/java/com/google/firebase/firestore/core/FirestoreClient.java

@@ -47,7 +47,7 @@
 import com.google.firebase.firestore.remote.RemoteSerializer;
 import com.google.firebase.firestore.remote.RemoteStore;
 import com.google.firebase.firestore.util.AsyncQueue;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 import com.google.firebase.firestore.util.Logger;
 import com.google.firestore.v1.Value;
 import java.io.InputStream;

firebase-firestore/src/main/java/com/google/firebase/firestore/core/SyncEngine.java

@@ -52,7 +52,7 @@
 import com.google.firebase.firestore.remote.RemoteStore;
 import com.google.firebase.firestore.remote.TargetChange;
 import com.google.firebase.firestore.util.AsyncQueue;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 import com.google.firebase.firestore.util.Logger;
 import com.google.firebase.firestore.util.Util;
 import com.google.firestore.v1.Value;

firebase-firestore/src/main/java/com/google/firebase/firestore/core/TransactionRunner.java

@@ -24,7 +24,7 @@
 import com.google.firebase.firestore.util.AsyncQueue;
 import com.google.firebase.firestore.util.AsyncQueue.TimerId;
 import com.google.firebase.firestore.util.ExponentialBackoff;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 
 /** TransactionRunner encapsulates the logic needed to run and retry transactions with backoff. */
 public class TransactionRunner<TResult> {

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLitePersistence.java

@@ -36,7 +36,7 @@
 import com.google.firebase.firestore.model.DatabaseId;
 import com.google.firebase.firestore.util.Consumer;
 import com.google.firebase.firestore.util.FileUtil;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 import com.google.firebase.firestore.util.Logger;
 import com.google.firebase.firestore.util.Supplier;
 import java.io.File;

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLiteRemoteDocumentCache.java

@@ -33,7 +33,7 @@
 import com.google.firebase.firestore.model.SnapshotVersion;
 import com.google.firebase.firestore.util.BackgroundQueue;
 import com.google.firebase.firestore.util.Executors;
-import com.google.firebase.firestore.util.Function;
+import com.google.common.base.Function;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.MessageLite;
 import java.util.ArrayList;