code: static ChangeEvent<BsonDocument> changeEventForLocalUpdate(
        final MongoNamespace namespace,
        final BsonValue documentId,
        final UpdateDescription update,
        final BsonDocument fullDocumentAfterUpdate,
        final boolean writePending
    ) {
      return new ChangeEvent<>(
          new BsonDocument(),
          OperationType.UPDATE,
          fullDocumentAfterUpdate,
          namespace,
          new BsonDocument("_id", documentId),
          update,
          writePending);
    }
docs: Generates a change event for a local update of a document in the given namespace referring
  to the given document _id.
  
  @param namespace the namespace where the document was inserted.
  @param documentId the _id of the document that was updated.
  @param update the update specifier.
  @return a change event for a local update of a document in the given namespace referring
  to the given document _id.