UnixSocketEndPoint should return local and remote SocketAddress

[joakime]

Currently, our UnixSocketEndPoint has null's for the local/remote endpoints.

https://github.com/eclipse/jetty.project/blob/jetty-9.4.8.v20171121/jetty-unixsocket/src/main/java/org/eclipse/jetty/unixsocket/UnixSocketEndPoint.java#L46-L56

If we can change those methods to return a java.net.SocketAddress then the
existing jnr.unixsocket.UnixSocketChannel can be used to obtain the local/remote UnixSocketAddress (which implements java.net.SocketAddress)

Hopefully these local/remote addresses can then be exposed in the HttpServletRequest local/remote address APIs.

[stale]

This issue has been automatically marked as stale because it has been a full year without activit. It will be closed if no further activity occurs. Thank you for your contributions.

[sbordet]

This is trivial to implement, as we have just have to delegate to the UnixSocketChannel passed to the constructor.

[joakime]

Seems like it, but it has a hitch ...

    @Override
    public InetSocketAddress getLocalAddress()
    {
        return _channel.getLocalAddress(); // fails, as this is just a SocketAddress, not a InetSocketAddress
    }

[joakime]

That's because a UnixSocket's SocketAddress is a file, and has nothing to do with Inet anything.

[sbordet]

Duplicated by #6410.