I need to see a test or snippet of what you are trying here. This PluralAttributePath object is only obtained by calling Path#get on the plural-attributes owner. Path#get returns an Expression. The method you are speaking of is defined on Path. So how did you get from Expression -> Path?

The problem here is really (I think) in the JPA contracts as far as being able to answer this question. That's the crux of the comment you mention.