src/vs/workbench/services/extensions/common/rpcProtocol.ts/RPCProtocol/getProxy
class RPCProtocol:	public getProxy<T>(identifier: ProxyIdentifier<T>): Proxied<T> {
		const { nid: rpcId, sid } = identifier;
		if (!this._proxies[rpcId]) {
			this._proxies[rpcId] = this._createProxy(rpcId, sid);
		}
		return this._proxies[rpcId];
	}