private void initializeHandlers(VisitorParameters params) {
        if (params.getLocalDataHandler() != null) {
            params.getLocalDataHandler().reset();
            params.getLocalDataHandler().setSession(this);
        } else if (params.getRemoteDataHandler() == null) {
            params.setLocalDataHandler(new VisitorDataQueue());
            params.getLocalDataHandler().setSession(this);
        }

        if (params.getControlHandler() != null) {
            params.getControlHandler().reset();
        } else {
            params.setControlHandler(new VisitorControlHandler());
        }
        params.getControlHandler().setSession(this);
    }
Called from the constructor to ensure control and data handlers
are set and initialized.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/MessageBusVisitorSession.java