I believe you are stepping through the service wm.tn.samples.broadcast:broadcastDeliver and get this error. This service expects bizdoc to be supplied as input which you cannot supply using Developer. So, you are not supplying anything as input and that could be the reason you are getting this error. Also, check that you are supplying correct partnerID to the service singleDeliver’s input bizdoc.
To run the broadcastDeliver service properly, you will need to first create a new wrapper service called runBroadcastDeliver.
In this service runBroadcastDeliver, create a input string called internalId.
Add the 1st step to invoke the service wm.tn.doc:view and set getContent flag to true.
Add the 2nd step to invoke the service wm.tn.samples.broadcast:broadcastDeliver.
Now open the TN Console and select any bizdoc which you want to send to multiple partner. Get the internalId of this bizdoc.
Now run and step through runBroadcastDeliver when asked, supply the internalId you got using the TN Console above.