Change event does not fire for FxRadioButtonGroup after setting selection to null

Steps to reproduce:
1. Compile & run:
<?xml version="1.0" encoding="utf-8"?>
<FxApplication
xmlns="http://ns.adobe.com/mxml/2009" xmlns:local="*"
backgroundColor="0xFFFFFF" >
<layout><VerticalLayout/></layout>

<Declarations>
<FxRadioButtonGroup id="srg" change="lbl.text='change fired'"/>
</Declarations>

<FxRadioButton id="s1" label="Spark 1" groupName="srg"/>
<FxRadioButton id="s2" label="Spark 2" groupName="srg"/>
<FxRadioButton id="s3" label="Spark 3" groupName="srg" selected="true"/>
<FxRadioButton id="s4" label="Spark 4" groupName="srg"/>
<FxRadioButton id="s5" label="Spark 5" groupName="srg"/>

<FxButton label="Set selection to null" click="srg.selection=null"/>

<Label id="lbl" />
</FxApplication>

2. Click on the "Set selection to null" button

Actual Results:
Label text does not update.

Expected Results:
Label text should say 'change fired' (change event does fire if you select a different FxRadioButton)

Workaround (if any):