'Return credentials checkers for this domain.
@rtype: L{list} of L{ICredentialsChecker
<checkers.ICredentialsChecker>} provider
@return: Credentials checkers for this domain.'

def getCredentialsCheckers(self):

    if (self._credcheckers is None):
        self._credcheckers = [DirdbmDatabase(self.dbm)]
    return self._credcheckers
