Port flaky test fix from web.
Port of
@@ -215,7 +215,8 @@ public class ServerTimestampTest {
DocumentSnapshot localSnapshot = accumulator.awaitLocalEvent();
assertEquals(42L, localSnapshot.get("a", ServerTimestampBehavior.PREVIOUS));
- docRef.update("a", FieldValue.serverTimestamp());
+ // include b=1 to ensure there's a change resulting in a new snapshot.
+ docRef.update("a", FieldValue.serverTimestamp(), "b", 1);
localSnapshot = accumulator.awaitLocalEvent();
assertEquals(42L, localSnapshot.get("a", ServerTimestampBehavior.PREVIOUS));
