@Override
    public void endProcessing() {
        LOGGER.debug("Processed {} XML ref data entries for ref stream", valueCount);
        try {
            if (stagingValueOutputStream != null) {
                LOGGER.debug("closing stagingValueOutputStream");
                stagingValueOutputStream.close();
            }
        } finally {
            super.endProcessing();
        }
    }
@param ch     An array of characters.
@param start  The starting position in the array.
@param length The number of characters to use from the array.
@throws SAXException The client may throw an exception during processing.
@see stroom.pipeline.filter.AbstractXMLFilter#characters(char[],
int, int)
stroom-state/stroom-state-impl/src/main/java/stroom/state/impl/pipeline/StateFilter.java