UserNameIterator ClusterClientCursorImpl::getAuthenticatedUsers() const {
    return makeUserNameIterator(_params.authenticatedUsers.begin(),
                                _params.authenticatedUsers.end());
}
 UserNameIterator AuthorizationSession::getImpersonatedUserNames() {
     return makeUserNameIterator(_impersonatedUserNames.begin(),
                                 _impersonatedUserNames.end());
 }