Comment made by: alexmiller
These are all immutable collections so I'm not talking about actual mutation, but about change from one immutable structure to another. There are several existing cases where we have immutable collections that don't support empty because it doesn't make conceptual sense, like record instances and map entries.
What I'm saying is that I believe this is one of those cases, regardless of whether the particular path of interfaces and impls allows the method to be called. Conceptually, bean creates an instance that is a read-only view of a Java object. It makes no sense to "empty" an object view - objects always have fields (this is the same argument with records, which have fixed fields, and map entries, which have key/value). I believe in ClojureScript there is actually a protocol that marks whether a collection can be emptied and perhaps that would make sense here as well.