@PipelineProperty(description = "Warn if there are duplicate keys found in the reference data?",
            defaultValue = "false",
            displayPriority = 1)
    public void setWarnOnDuplicateKeys(final boolean warnOnDuplicateKeys) {
        this.warnOnDuplicateKeys = warnOnDuplicateKeys;
    }
@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 org.xml.sax.SAXException The client may throw an exception during processing.
@see stroom.pipeline.filter.AbstractXMLFilter#characters(char[],
int, int)
stroom-pipeline/src/main/java/stroom/pipeline/refdata/ReferenceDataFilter.java