src/vs/platform/tunnel/common/tunnel.ts/AbstractTunnelService/addTunnelToMap
class AbstractTunnelService:	protected addTunnelToMap(remoteHost: string, remotePort: number, tunnel: Promise<RemoteTunnel | undefined>) {
		if (!this._tunnels.has(remoteHost)) {
			this._tunnels.set(remoteHost, new Map());
		}
		this._tunnels.get(remoteHost)!.set(remotePort, { refcount: 1, value: tunnel });
	}