if (value != null) {
            return value;
        }
        return get("elasticsearch.username");
    }

    String getSearchEnginePassword();

    default String getFesenPassword() {
        final String value = getSearchEnginePassword();
        if (value != null) {
            return value;
        }
        return get("elasticsearch.password");
    }

     * comment: Password for authenticating to the search engine.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getSearchEnginePassword();

    /**
     * Get the value for the key 'search_engine.password' as {@link Integer}. <br>
     * The value is, e.g.  <br>
     * comment: Password for authenticating to the search engine.