Offset logline (#3417)

Author: schmidt-sebastian

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

@@ -135,6 +135,7 @@ private int writeEntriesForCollectionGroup(
     indexManager.updateIndexEntries(nextBatch.getDocuments());
 
     IndexOffset newOffset = getNewOffset(existingOffset, nextBatch);
+    Logger.debug(LOG_TAG, "Updating offset: %s", newOffset);
     indexManager.updateCollectionGroup(collectionGroup, newOffset);
 
     return nextBatch.getDocuments().size();