'Make sure that we add a tag that Ceilometer can pick up.
These need to be prepended with \'metering.\'.'

def _tags(self):

    tags = (self.properties.get(self.TAGS) or [])
    for t in tags:
        if t[self.TAG_KEY].startswith('metering.'):
            return tags
    return (tags + [{self.TAG_KEY: 'metering.groupname', self.TAG_VALUE: self.FnGetRefId()}])
