@Override
    public void endPrefixMapping(final String prefix) throws SAXException {
        if (handler != null) {
            handler.endPrefixMapping(prefix);
        } else if (passThrough) {
            super.endPrefixMapping(prefix);
        }
    }
the prefix that was being mapped. This is the empty string when a default
mapping scope ends.

@param prefix the prefix that was being mapped. This is the empty string
              when a default mapping scope ends.
@throws org.xml.sax.SAXException the client may throw an exception during processing
@see #startPrefixMapping
@see #endElement
@see stroom.pipeline.filter.AbstractXMLFilter#endPrefixMapping(java.lang.String)
stroom-pipeline/src/main/java/stroom/pipeline/filter/XsltFilter.java