'Callback to handle RBAC_POLICY, BEFORE_UPDATE callback.
:raises: RbacPolicyInUse -- in case the update is forbidden.'

@classmethod
def validate_rbac_policy_update(cls, resource, event, trigger, context, object_type, policy, **kwargs):

    prev_tenant = policy['target_tenant']
    new_tenant = kwargs['policy_update']['target_tenant']
    if (prev_tenant == new_tenant):
        return
    if (new_tenant != '*'):
        return cls.validate_rbac_policy_delete(resource, event, trigger, context, object_type, policy)
