src/vs/workbench/services/extensions/common/rpcProtocol.ts/MessageIO/serializeReplyOK
class MessageIO:	public static serializeReplyOK(req: number, res: any, replacer: JSONStringifyReplacer | null): VSBuffer {
		if (typeof res === 'undefined') {
			return this._serializeReplyOKEmpty(req);
		}
		if (res instanceof VSBuffer) {
			return this._serializeReplyOKVSBuffer(req, res);
		}
		return this._serializeReplyOKJSON(req, safeStringify(res, replacer));
	}