@Override
    public void startStream() {
        super.startStream();
        LOGGER.debug("StartStream called");
    }
This XML filter captures XML content that defines key, value maps to be
stored as reference data. The key, value map content is likely to have been
produced as the result of an XSL transformation of some reference data.
<p>
This filter will typically fire
stroom-state/stroom-state-impl/src/main/java/stroom/state/impl/pipeline/StateFilter.java