LRARecord has...
case "javax.ws.rs.PUT":
return asyncInvoker.put(Entity.text(null));
whereas entity should never be null for PUT
I see this comment has been there since the code was first added and so perhaps this is the desired...
// return asyncInvoker.put(Entity.entity(compensatorData, mediaType));
If not perhaps simply Entity.text("") should suffice (and has in my tests).