Functional style

Author: wu-hui

firebase-firestore/src/test/java/com/google/firebase/firestore/local/LocalStoreTestCase.java

@@ -74,11 +74,13 @@
 import com.google.firebase.firestore.testutil.TestUtil;
 import com.google.firebase.firestore.util.AsyncQueue;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.stream.Collectors;
 import javax.annotation.Nullable;
 import org.junit.After;
 import org.junit.Assert;
@@ -161,12 +163,12 @@ private void acknowledgeMutationWithTransformResults(
         Collections.singletonList(new MutationResult(version, emptyList()));
 
     if (transformResult.length != 0) {
-      mutationResults = new ArrayList<>();
-      for (Object o : transformResult) {
-        mutationResults.add(
-            new MutationResult(version, Collections.singletonList(TestUtil.wrap(o))));
-      }
+      mutationResults =
+          Arrays.stream(transformResult)
+              .map(r -> new MutationResult(version, Collections.singletonList(TestUtil.wrap(r))))
+              .collect(Collectors.toList());
     }
+
     MutationBatchResult result =
         MutationBatchResult.create(batch, version, mutationResults, WriteStream.EMPTY_STREAM_TOKEN);
     lastChanges = localStore.acknowledgeBatch(result);