languageHelper.updateDocument(doc);

        assertEquals("ja", doc.get("lang"));
        assertEquals("タイトル", doc.get("title_ja"));
        assertEquals(123, doc.get("content_ja"));
        assertNull(doc.get("url_ja")); // url is not in langFields
    }

    public void test_updateDocument_withNullLangFields() {
        Map<String, Object> doc = new HashMap<>();
        doc.put("lang", "ja");
        doc.put("title", null);

        }

        /**
         * @return URL
         */
        public URL getURL() {
            return url_;
        }

        /**
         * @param url
         */
        public void setURL(final URL url) {
            url_ = url;
        }

        /**
         * @return Returns the cal.
         */
        public Calendar getCal() {