Method serialize

flow/include/flow/ObjectSerializer.h:213–234

	}
	template <class... Items>
	void serialize(FileIdentifier file_identifier, Items const&... items) {
		int allocations = 0;
		auto allocator = [this, &allocations](size_t size_) {
			++allocations;
			this->size = writeProtocolVersion ? size_ + sizeof(uint64_t) : size_;
			if (customAllocator) {
				data = customAllocator(this->size);
			} else {
				data = new (arena) uint8_t[this->size];
			}
			if (writeProtocolVersion) {
				auto v = protocolVersion().versionWithFlags();
				memcpy(data, &v, sizeof(uint64_t));
				return data + sizeof(uint64_t);
			}
			return data;
		};
		ASSERT(data == nullptr); // object serializer can only serialize one object
		SaveContext<ObjectWriter, decltype(allocator)> context(this, allocator);
		save_members(context, file_identifier, items...);
		ASSERT(allocations == 1);
	}

	template <class Item>
	void serialize(Item const& item) {