@Override
    public void startPrefixMapping(final String prefix, final String uri) throws SAXException {
        try {
            prefixes.put(prefix, uri);

            if (validator != null) {
                validator.startPrefixMapping(prefix, uri);
            }
        } catch (final RuntimeException e) {
            unexpectedError("startPrefixMapping()", e);
        } finally {
            super.startPrefixMapping(prefix, uri);
        }
    }
Adds prefixes from the prefix map.

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