@Override
    public void processingInstruction(final String target, final String data) throws SAXException {
        super.processingInstruction(target, data);
        cb.append(PROCESSING_INSTRUCTION);
        cb.append(target);
        cb.append(DELIMITER);
        cb.append(data);
        writeln(cb);
    }
@param target the processing instruction target
@param data   the processing instruction data, or null if none was supplied.
              The data does not include any whitespace separating it from
              the target
@throws org.xml.sax.SAXException any SAX exception, possibly wrapping another exception
stroom-pipeline/src/main/java/stroom/pipeline/filter/TestSAXEventFilter.java