HTTPService XML contentType and Gets

I have a flex front-end in which I'm trying to get data from a back-end using an HTTPService. I would like the service to use a GET, and make the request using the contenttype of application/xml. So for example here's an HTTPService that does this:
<mx:HTTPService id="testService"
url="/blah/list"
contentType="application/xml"
method="GET"/>

When I go ahead and do the request (using testService.send()) it always does the request as a POST. If I change the HTTPService's contentType to "application/x-www-form-urlencoded" it works correctly as a GET.

Does anyone have any pointers on how I could get this to work the way I want it? Is this a flex bug or an undocumented feature somewhere? Any workarounds?

Thanks.

Here is the output I get when I put an <mx:TraceTarget> in the app with the contentType="application/xml":
(mx.messaging.messages::HTTPRequestMessage)#0
body = "<>"
clientId = (null)
contentType = "application/xml"
destination = "DefaultHTTP"
headers = (Object)#1
httpHeaders = (Object)#2
messageId = "3EB110BB-955A-9601-C595-C14D38E12C14"
method = "POST"
recordHeaders = false
timestamp = 0
timeToLive = 0
url = "/pools/list"