return requiredValidator.isValid(value, null);
    }

    String getCrawlerDocumentSpaceChars();

    default int[] getCrawlerDocumentSpaceCharsAsArray() {
        return getCrawlerDocumentCharsAsArray(CRAWLER_DOCUMENT_SPACE_CHARS, getCrawlerDocumentSpaceChars());
    }

    default String[] getCrawlerDocumentSpaces() {

    public void test_getCrawlerDocumentSpaceCharsAsArray() {
        FessProp.propMap.clear();
        FessConfig fessConfig = new FessConfig.SimpleImpl() {
            @Override
            public String getCrawlerDocumentSpaceChars() {
                return "u0020u3000";
            }
        };

        int[] chars = fessConfig.getCrawlerDocumentSpaceCharsAsArray();
        assertEquals(2, chars.length);

     * comment: Unicode space characters for document parsing.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getCrawlerDocumentSpaceChars();

    /**
     * Get the value for the key 'crawler.document.fullstop.chars'. <br>
     * The value is, e.g. u002eu06d4u2e3cu3002 <br>
     * comment: Unicode full stop characters for document parsing.