LocalStore.java

// LocalDocumentsView.java

Document getDocument(DocumentKey key) {
  // 1. Get all mutations for the given document
  List<MutationBatch> batches = mutationQueue.getAllMutationBatchesAffectingDocumentKey(key);
  return getDocument(key, batches);
}

private Document getDocument(DocumentKey key, List<MutationBatch> inBatches) {
  // 2. Fetch the remote version of the given document from the local cache
  MutableDocument document = remoteDocumentCache.get(key);
  for (MutationBatch batch : inBatches) {
    // 3. Apply all mutations to the remote document
    batch.applyToLocalView(document);
  }
  return document; // = RemoteDocument + Active(LocalMutations)
}