EMPTY selector.

Author: kinyoklion

lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/PollingBase.java

@@ -80,7 +80,7 @@ protected CompletableFuture<FDv2SourceResult> poll(Selector selector, boolean on
             if (pollingResponse == null) {
                 return FDv2SourceResult.changeSet(
                         new DataStoreTypes.ChangeSet<>(DataStoreTypes.ChangeSetType.None,
-                                null,
+                                Selector.EMPTY,
                                 null,
                                 // TODO: Implement environment ID support.
                                 null