That is part of ODI requirements. If you look at Xbaya monitor messages the sendresults notification are empty. Can you please explain the purpose of sendresults notification? If it not used it should be removed to avoid confusion.
These notifications doesn't have the output but we have node specific outputs in receivedResults notification messages. And more importantsly we do not recommend users to get workflow inputs outputs from notifications, Best way is to query them from registry.
Uptil the current version of Airavata, the way to get outputs is to use the Airavata API and query the registry. The notifications are for notification purposes only. If this needs to be changed I suggest to discuss this in the mailing list first. There may be solutions, but I think this needs to go to 0.7 or later.