@Override
    boolean processUnknowPacket(Element doc) throws UnauthorizedException {
        // Handle subsequent db:result packets
        if ("db".equals(doc.getNamespacePrefix()) && "result".equals(doc.getName())) {
            if (!((LocalIncomingServerSession) session).validateSubsequentDomain(doc)) {
                throw new UnauthorizedException("Failed to validate domain when using piggyback.");
            }
            return true;
        }
        else if ("db".equals(doc.getNamespacePrefix()) && "verify".equals(doc.getName())) {
            // The Receiving Server is reusing an existing connection for sending the
            // Authoritative Server a request for verification of a key
            ((LocalIncomingServerSession) session).verifyReceivedKey(doc);
            return true;
        }
        return false;
    }
Controls if JIDs that are in the addresses of stanzas supplied by remote domains are validated.
xmppserver/src/main/java/org/jivesoftware/openfire/net/ServerStanzaHandler.java