couple of proton Messenger questions.

I was wondering about how one might translate some of the
qpid::Messaging connection options to Messenger

It seems like the SASL options are currently a non-starter and that
Messenger will use anonymous or PLAIN if user:pass is set, but am I
correct that there's no support for other mechanisms?

In qpid-config I came across conn_options['client_properties'] =
{'qpid.ha-admin' : 1} which suggests an ha-admin property is able to be
used, but TBH a bit of grepping around the qpid Messaging code left me a
bit stumped as to how that property actually gets passed around I found
src/qpid/ha/ConnectionObserver.cpp:const std::string
ConnectionObserver::ADMIN_TAG="qpid.ha-admin";
But how things get passed from connection options to the
ConnectionObserver I have no clue, so rather than trying to reverse
engineer it I figured I'd simply ask whether there is a mechanism to
make use of that mechanism in proton Messenger vice qpid::Messaging, and
if so what's the magic incantation???

Next am I correct that there is still no mechanism to specify "fancy"
link options in pI can subscribe to receive messages from a simple Node
address but say I want to subscribe to a particular subject say
amq.topic/UK.WEATHER and the like, that's pretty easy via an Address
String in qpid::Messaging or JMS but it still doesn't seem possible with
Messenger?

Finally, is it possible to un-subscribe an address? Say I've got code
that does
subscription = messenger.subscribe('amqp://0.0.0.0:5672/#');

That creates a temporary queue on my broker and I can eventually get the
subscription Address, but once I'm done there doesn't seem to be a way
to finish with the subscription short of actually stopping the
Messenger, have I missed something?

Cheers,
Frase