protected Set<JID> getBlocklist( User user )
    {
        Log.debug( "Retrieving all JIDs that are on the blocklist of user '{}'.", user.getUsername() );
        final PrivacyList defaultPrivacyList = PrivacyListManager.getInstance().getDefaultPrivacyList( user.getUsername() );
        if ( defaultPrivacyList == null )
        {
            return Collections.emptySet();
        }

        return defaultPrivacyList.getBlockedJIDs();
    }
Retrieves all of the JIDs that are on the blocklist of the provided user.

@param user The use for which to retrieve the blocklist (cannot be null).
@return The JIDs that are on the blocklist (possibly empty, but never null).
xmppserver/src/main/java/org/jivesoftware/openfire/handler/IQBlockingHandler.java