*/
    public static String defaultString(final String str, final String defaultStr) {
        return str == null ? defaultStr : str;
    }

    /**
     * <p>Checks if the CharSequence contains only ASCII printable characters.</p>
     *
     * <p>{@code null} will return {@code false}.
     * An empty CharSequence (length()=0) will return {@code true}.</p>
     *
     * <pre>

    }


    @Test
    public void testAES256Checksum () throws GeneralSecurityException {
        String data = "fourteen";
        String key = "B1AE4CD8462AFF1677053CC9279AAC30B796FB81CE21474DD3DDBCFEA4EC76D7";
        String expect = "E08739E3279E2903EC8E3836";
        verifyAESHMAC(4, expect, key, data.getBytes(StandardCharsets.US_ASCII));
    }


    /**

                    && (!getFessConfig().isCrawlerDocumentUseSiteEncodingOnEnglish()
                            || ("ISO-8859-1".equalsIgnoreCase(encoding) || "US-ASCII".equalsIgnoreCase(encoding)))) {
                enc = getFessConfig().getCrawlerDocumentSiteEncoding();
            } else {
                enc = encoding;
            }

            try {