Property folding has trouble with coalesce

This appears closely related to TINKERPOP-2112. I had some working code that was appending .property(T.id, str) to the results of an addE call. However, I have refactored that code so that the call to set the ID is appended to a coalesce call:

gts.V(Vo).coalesce(
  // guard condition
  __.addE("rel").to(Vi).property("foo", bar)
);

This formulation triggers the same T$2 cannot be cast to String error.