Unable to replace expression in flowable http task url, headers

Flowable Engine
1 
	<serviceTask id="createSupplyInitiatedProposal"
		name="create Supply Initiated Proposal" flowable:type="http">
		<extensionElements>
			<flowable:field name="requestMethod">
				<flowable:string><![CDATA[GET]]></flowable:string>
			</flowable:field>
			<flowable:field name="requestUrl">
				<flowable:string><![CDATA[http://localhost:8008/test1/${proposalId}]]></flowable:string>
			</flowable:field>
			<flowable:field name="requestHeaders">
				<flowable:string><![CDATA[

orgKey:${orgKey}
application-origin:hardcode origin1]]></flowable:string>

2

How was the XML created? Through our modeler or manually?

I would assume that if you change

<flowable:string><![CDATA[http://localhost:8008/test1/${proposalId}]]></flowable:string>

with

<flowable:expression><![CDATA[http://localhost:8008/test1/${proposalId}]]></flowable:expression>

then it would work.

Edit: pressed enter too soon