When using GET to get a message it does not return any of the JMS message properties.
I can easily see how to add that code, but I'm not sure what the correct way to return them is. They could go into the response headers via setResponseHeaders or the returned XML format could be changed to support properties and the header. Sadly this would likely break most existing clients.
We'd like to use the REST API to enable some web clients to fully participate in a messaging system that is primarily Java based.
If we can come to agreement on how we want to return properties then I'd be happy to code up a patch.