for _, pcs := range tr.idleConn {
		for _, pc := range pcs {
			pc.conn.Close()
		}
	}
	tr.idleMu.Unlock()
}

// ResponseWriterConnForTesting returns w's underlying connection, if w
// is a regular *response ResponseWriter.
func ResponseWriterConnForTesting(w ResponseWriter) (c net.Conn, ok bool) {
	if r, ok := w.(*response); ok {
		return r.conn.rwc, true
	}
	return nil, false
}

	w.Write([]byte(r.RemoteAddr))

	// Include the address of the net.Conn in addition to the RemoteAddr,
	// in case kernels reuse source ports quickly (see Issue 52450)
	if c, ok := ResponseWriterConnForTesting(w); ok {
		fmt.Fprintf(w, ", %T %p", c, c)
	}
})

// testCloseConn is a net.Conn tracked by a testConnSet.
type testCloseConn struct {
	net.Conn
	set *testConnSet
}