Flex HTTP header customization problems again

So, again I hit Flex's HTTP networking constraint -- HTTPService rather than URLRequest this time.
HTTPService does not seem to allow modification of certain headers, amongst them the "Accept" header (it was "Cookie" last time for URLRequest).  Specific need: to call a RESTful webservice with "application/json" before "text/html" in the list (otherwise, I get back HTML!).

URLRequestHeader's documentation semi-explains about one only being able to change certain headers when in a certain sandbox/ApplicationDomain.  Curiously, HTTPService doesn't mention -- just doesn't do!

Ahha, thanks to good doc in URLRequestHeader (the class that let me down for my "Cookie" need last time), I find URLRequest does support a "requestHeader" property.  Perhaps there is light.

<time passes...>

Yup, that seems to work.  Switched from HTTPService to use of a URLLoader and things now behave.  This brings the function size and scope up radically so time to refactor into a JSONCallHelper class (yes, possible name refactoring pending).

An aside: I checked AdobeTed/Ted Patrick's FDOT library (here, here and here) and it seems pretty similar goal -- albeit without the header specification but it looks reasonable to retrofit for an offered commit.  Will puruse this slightly before then.

Next, that my FlexUnit4 Test(async,timeout=2000) doesn't actually wait 2 seconds to see whether my method wants to do anything else.  Reckon I must be misunderstanding its intent (or else those Async.proceedOnEvent() family of methods need using?!).  This article's mention of proceedOnEvent() indicates the answer -- one does need to call one of the Async methods so the framework knows (this recipe also looked handy but might be out of date.)  I ended up with the following kludge while still exposing the asynchronicity of the tested method:

  const timer:Timer = new Timer(5000);
  timer.start();
  Async.proceedOnEvent(this, timer, TimerEvent.TIMER_COMPLETE, 8000, function(event:TimerEvent):void{
    trace("timer done");
  });

Well, looks like I've overcome it for now.