public synchronized  void add(Permission permission) 
{
        if (!(permission instanceof MBeanServerPermission)) {
            final String msg =
                "Permission not an MBeanServerPermission: " + permission;
            throw new IllegalArgumentException(msg);
        }
        if (isReadOnly())
            throw new SecurityException("Read-only permission collection");
        MBeanServerPermission mbsp = (MBeanServerPermission) permission;
        if (collectionPermission == null)
            collectionPermission = mbsp;
        else if (!collectionPermission.implies(permission)) {
            int newmask = collectionPermission.mask | mbsp.mask;
            collectionPermission = new MBeanServerPermission(newmask);
        }
}

 public synchronized Enumeration<Permission> elements() 
{
        Set< Permission > set;
        if (collectionPermission == null)
            set = Collections.emptySet();
        else
            set = Collections.singleton((Permission) collectionPermission);
        return Collections.enumeration(set);
}

 public synchronized boolean implies(Permission permission) 
{
        return (collectionPermission != null &&
                collectionPermission.implies(permission));
}