The question as posted. There is a blueprint node called GetAllActorsOfClass, but I need a method along the lines of GetAllActorsoOfInterface. What is the best way to list all the actors in my map that implement a specific interface?
There is a node called GetAllActorsWithWithInterface 
Hope this helps
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Ack! I was googling GetallactorsOFinterface. Sorry for the trivial question but many thanks for pointing that out.