Settings for Karabiner to enable Shift+Enter shortcut for newline in Messages app

private.xml

<?xml version="1.0"?>
<!-- Documentation: https://pqrs.org/osx/karabiner/xml.html.en -->
<root>
	<appdef>
		<appname>Messages</appname>
		<equal>com.apple.iChat</equal>
	</appdef>
	<item>
		<name>Enable Shift+enter newline shortcut in Messages app</name>
		<identifier>private.Messages.NewLine</identifier>
		<uielementrole_only>AXTextArea</uielementrole_only>
		<only>Messages</only>
		<autogen>
			__KeyToKey__ 
			KeyCode::RETURN, ModifierFlag::SHIFT_L | ModifierFlag::NONE, 
			KeyCode::RETURN, ModifierFlag::OPTION_L
		</autogen>
	</item>
</root>

Thank you!