API Group.replaceMembers() doesn't work with privileges

Method Group.replaceMembers(Collection<Subject> newSubjectList, Field field) – you can pass in a Field, but the only field that works is members. If you pass in a readers or updaters field, it throws a SchemaException error, because internal_addMember() is specifically rejecting non-list types.

There is a web service that can replace privileges (WsRestAssignGrouperPrivilegesRequest), but no API equivalent. It would be nice to have an API method to sync privileges using the existing algorithms, rather than having to rewrite it in caller code.