The error: "The method
arrayByAddingObjectsFromArray(NSArray<EOProperty>) in the type
NSArray<EOProperty> is not applicable for the arguments
(NSArray<EOAttribute>)". Say what?! An EOAttribute is an EOProperty!
The cause of this compiler error has been confirmed to be a WO 5.4
bug related to an improper declaration involving Java generics.
Genericizing one's code correctly can be tricky stuff, but I think
that most of such bugs can be worked around until they're fixed.