@Override
    public void processingInstruction(final String target, final String data) throws SAXException {
        if (handler != null) {
            handler.processingInstruction(target, data);
        } else {
            super.processingInstruction(target, data);
        }
    }
Buffers a processingInstruction event if buffer is set to true.

@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 SAXException Not thrown.
@see stroom.pipeline.filter.AbstractXMLFilter#processingInstruction(java.lang.String,
java.lang.String)
stroom-pipeline/src/main/java/stroom/pipeline/filter/BufferFilter.java