public function getIdentityRoles()
    {
        if (!$identity = $this->getIdentity()) {
            return $this->convertRoles([$this->guestRole]);
        }

        if (!$identity instanceof IdentityInterface) {
            throw new Exception\RuntimeException(sprintf(
                'ZfcRbac expects your identity to implement ZfcRbac\Identity\IdentityInterface, "%s" given',
                is_object($identity) ? get_class($identity) : gettype($identity)
            ));
        }

        return $this->convertRoles($identity->getRoles());
    }