@Override
    public void startPrefixMapping(final String prefix, final String uri) throws SAXException {
        if (contentHandler != null) {
            contentHandler.startPrefixMapping(prefix, uri);
        }

        prefixMappings.put(prefix, uri);
        compiler.declareNamespace(prefix, uri);

        super.startPrefixMapping(prefix, uri);
    }
Fired when a prefix mapping is in scope.

@param prefix The prefix.
@param uri    The URI of the prefix.
@throws SAXException Not thrown.
@see stroom.pipeline.filter.AbstractXMLFilter#startPrefixMapping(java.lang.String,
java.lang.String)
stroom-search/stroom-search-extraction/src/main/java/stroom/search/extraction/XPathExtractionOutputFilter.java