How do I see the message for a http-response-code 406 exception

How do I see the message for a http-response-code 406 exception

I'm using ColdFusion but I think this is more a java question. I'm making
an xml post to a web service. When I attempt to read the response I
receive an exception with an http response code of 406 from the following
line:
var inputStreamReader =
CreateObject("java","java.io.InputStreamReader").init(variables.connection.getInputStream());
The web service doc says the following for 406: "A 406 will be returned if
the request was processed but did contained invalid or insufficient
information to completed the API method. A message will be returned
describing the error."
My question is, how do I retrieve or otherwise see what the message
content contains?