// value.
	ConnContext func(ctx context.Context, c net.Conn) context.Context

	inShutdown atomic.Bool // true when server is in shutdown

	disableKeepAlives atomic.Bool
	nextProtoOnce     sync.Once // guards setupHTTP2_* init
	nextProtoErr      error     // result of http2.ConfigureServer if used

	mu         sync.Mutex
	listeners  map[*net.Listener]struct{}
	activeConn map[*conn]struct{}