throws DataBackendException, UnknownEntityException
{
Iterator groupsIterator = getAllGroups().iterator();
while (groupsIterator.hasNext())
{
Group group = (Group) groupsIterator.next();
Iterator rolesIterator = getRoles(user, group).iterator();
while (rolesIterator.hasNext())
{
Role role = (Role) rolesIterator.next();
revoke(user, group, role);