Method describe

src/ExtMsg.actor.cpp:1431–1431

	ExtSimpleUpsert(bson::BSONObj selector, bson::BSONObj update) : selector(selector), update(update) {}

	std::string describe() override { return "SimpleUpsert(" + selector.toString() + "," + update.toString() + ")"; }

	Future<Reference<IReadWriteContext>> insert(Reference<CollectionContext> cx) override {
		Optional<IdInfo> encodedIds = extractEncodedIds(selector);