private void sendPresence( User user, Set<JID> recipients )
    {
        if ( recipients.isEmpty() )
        {
            return;
        }

        final PresenceManager presenceManager = XMPPServer.getInstance().getPresenceManager();
        final Presence presence = presenceManager.getPresence( user );
        if ( presence == null )
        {
            return;
        }

        for ( final JID recipient : recipients )
        {
            try
            {
                if ( presenceManager.canProbePresence( recipient, user.getUsername() ) )
                {
                    presenceManager.probePresence( recipient.asBareJID(), XMPPServer.getInstance().createJID( user.getUsername(), null ) );
                }
            }
            catch ( UserNotFoundException e )
            {
                Log.error( "Unable to send presence information of user '{}' to unblocked entity '{}' as local user is not found.", user.getUsername(), recipient );
            }
        }
    }
Sends current presence information of the local user to the a collection of JIDs, if appropriate.

@param user       The use for which to send presence (cannot be null).
@param recipients The entities to which information is send (cannot be null, can be empty)
xmppserver/src/main/java/org/jivesoftware/openfire/handler/IQBlockingHandler.java