Titanium Mobile properly serializing JSON into a query string

xhr_json_post.js

var url = "http://localhost:3000";
var params = { 
	foo: 'bar',
	stuff: [1,2,3]
};
var xhr = Ti.Network.createHTTPClient({
	onload: function() {
		alert("load!");
	},
	onerror: function() {
		alert("error!");
	}
});

xhr.open('POST', url);
xhr.setRequestHeader("Content-Type","application/json");
params = JSON.stringify(params);
xhr.send(params);

// parameters from Rails log:
// Parameters: {"stuff"=>[1, 2, 3], "action"=>"index", "foo"=>"bar", "controller"=>"home"}

// NOTE:
// parameters will be garbled without the application/json Content-Type
// parameters will also be garbled without JSON.stringify, even though the Titanium docs say that xhr.send() should do this automatically