Bas, you will need two nodes to create a msg object with the "complete" property set -- use an inject node to create a msg with the payload set to a boolean 'true' value -> pass that to a change node that moves the msg.payload to msg.complete
There was a suggestion a while back to allow the inject node to ouput on any msg property (not just payload), but that is not available yet. And since there is a simple 2-node work-around, it has not bubbled up the priority list yet (and may never happen, to be honest)
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Steve