'Detailed view of a single volume.'

def detail(self, request, volume):

    volume_ref = super(ViewBuilder, self).detail(request, volume)
    req_version = request.api_version_request
    if req_version.matches('3.13', None):
        volume_ref['volume']['group_id'] = volume.get('group_id')
    if (request.environ['cinder.context'].is_admin and req_version.matches('3.21', None)):
        volume_ref['volume']['provider_id'] = volume.get('provider_id')
    return volume_ref
