Method update

src/ExtMsg.actor.cpp:1348–1350

	explicit ExtOperatorUpdate(bson::BSONObj const& msgUpdate) : msgUpdate(msgUpdate) {}

	Future<Void> update(Reference<IReadWriteContext> document) override {
		return updateDocument(document, msgUpdate, false, document->getKeyEncodedId());
	}

	std::string describe() override { return "OperatorUpdate(" + msgUpdate.toString() + ")"; }
};