https://host:port/odata/applications/{latest|v1/}{appid}/Connections/('{appcid}')
Method : PUT
HTTP Headers "Content-Type" = "application/atom+xml" and "X-HTTP-METHOD" = "PUT"
Body:
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">
<content type="application/xml">
<m:properties>
<d:MpnsChannelURI>{MPNS Channel URI}</d:MpnsChannelURI>
</m:properties>
</content>
</entry>