Missing commas when several spaces are present in a spaces parameter

<ac:structured-macro ac:name="outgoing-links">
    <ac:parameter ac:name="spaces"><ri:space ri:space-key="DEMO" /><ri:space ri:space-key="TEST" /></ac:parameter>
</ac:structured-macro>

{{outgoing-links spaces="DEMOTEST"/}}

{{outgoing-links spaces="DEMO,TEST"/}}