'Updates the connector on the volume attachment. An attachment
without a connector is considered reserved but not fully attached.
:param context: The nova request context.
:param attachment_id: UUID of the volume attachment to update.
:param connector: host connector dict. This is required when updating
a volume attachment. To terminate a connection, the volume
attachment for that connection must be deleted.
:returns: a dict created from the
cinderclient.v3.attachments.VolumeAttachment object with a backward
compatible connection_info dict'

@translate_attachment_exception
def attachment_update(self, context, attachment_id, connector):

    try:
        attachment_ref = cinderclient(context, '3.27', skip_version_check=True).attachments.update(attachment_id, connector)
        return _translate_attachment_ref(attachment_ref.to_dict())
    except cinder_exception.ClientException as ex:
        with excutils.save_and_reraise_exception():
            LOG.error('Update    attachment    failed    for    attachment    %(id)s.    Error:    %(msg)s    Code:    %(code)s', {'id': attachment_id, 'msg': six.text_type(ex), 'code': getattr(ex, 'code', None)})
