def __parse_blacklist(self, json):
        try:
            for entry in json['blacklist']:
                if not entry:
                    msg = "invalid json format. Blacklist entries cannot be null or empty"
                    raise InvalidFormatError(cause=msg)
                excluded = self.__encode(entry)
                bl = self._blacklist.get(excluded, None)
                if not bl:
                    bl = MatchingBlacklist(excluded=excluded)
                    self._blacklist[excluded] = bl
        except KeyError as e:
            msg = "invalid json format. Attribute %s not found" % e.args
            raise InvalidFormatError(cause=msg)