protected DispatchHandler getDispatchHandler() {
        if (dispatchHandler == null) {
            dispatchHandler = new DispatchHandler();
        }
        return dispatchHandler;
    }
Returns the last time a full Document was read or a heartbeat was received. Hearbeats
are represented as whitespaces or \n received while a Document is not being parsed.

@return the time in milliseconds when the last document or heartbeat was received.
xmppserver/src/main/java/org/dom4j/io/XMPPPacketReader.java