public void setCacheDuration(final long cacheDuration) {
        this.cacheDuration = cacheDuration;
    }

    private static final class DefaultNamespaceContext implements NamespaceContext {

        private final Node doc;

        public DefaultNamespaceContext(final Node doc) {
            this.doc = doc;
        }

        @Override
        public String getNamespaceURI(final String prefix) {