Document expectations about NameResolver SocketAddresses

[carl-mastrangelo]

Currently, a name resolver returns a collection of SocketAddress wrapped up in EquivalentAddressGroups. In the most common case InetSocketAddress will be used. Currently there are no expectations about the data in the address, but I believe we need to clarify this.

This came up in working with HTTP Proxies. In case a Proxy is used, Netty can derive the the initial CONNECT message from the InetSocketAddress hostname. This may be present or may not, but the behavior of this may change based on what the name resolver returns.

I don't know what to say here, other than it may be absent, but I wanted to open up a discussion because it recently came up.

[carl-mastrangelo]

cc @ejona86 @zhangkun83

[ejona86]

Right now it's basically "use InetSocketAddress" as everything else won't work. But as was mentioned in that other discussion #3085 will open of more alternatives.

So I'm not really sure what you're hoping will happen before #3085 is done.