src/vs/workbench/services/extensions/common/rpcProtocol.ts/MessageIO/_serializeReplyOKJSONWithBuffers
class MessageIO:	private static _serializeReplyOKJSONWithBuffers(req: number, res: string, buffers: readonly VSBuffer[]): VSBuffer {
		const resBuff = VSBuffer.fromString(res);

		let len = 0;
		len += MessageBuffer.sizeUInt32; // buffer count
		len += MessageBuffer.sizeLongString(resBuff);
		for (const buffer of buffers) {
			len += MessageBuffer.sizeVSBuffer(buffer);
		}

		let result = MessageBuffer.alloc(MessageType.ReplyOKJSONWithBuffers, req, len);
		result.writeUInt32(buffers.length);
		result.writeLongString(resBuff);
		for (const buffer of buffers) {
			result.writeBuffer(buffer);
		}

		return result.buffer;
	}