@Override
    public void ignorableWhitespace(final char[] ch, final int start, final int length) throws SAXException {
        if (buffer) {
            events.add(new IgnorableWhitespace(ch, start, length));
        } else {
            super.ignorableWhitespace(ch, start, length);
        }
    }
Buffers a ignorableWhitespace event if buffer is set to true.

@param ch     the characters from the XML document
@param start  the start position in the array
@param length the number of characters to read from the array
@throws SAXException Not thrown.
@see stroom.pipeline.filter.AbstractXMLFilter#ignorableWhitespace(char[],
int, int)
stroom-pipeline/src/test/java/stroom/pipeline/util/BufferFilter.java