'Migrate a v2 JSON configuration to v3.
:param bytes config: The v2 JSON data.
:return bytes: The v3 JSON data.'

@classmethod
def upgrade_from_v2(cls, config):

    decoded_config = loads(config)
    decoded_config[u'version'] = 3
    decoded_config[u'deployment'][u'leases'] = {u'values': [], _CLASS_MARKER: u'PMap'}
    return dumps(decoded_config)
