// Test characters just outside ranges that are not valid
        assertFalse(CharUtil.isUrlChar('`')); // backtick (just before 'a')
        assertFalse(CharUtil.isUrlChar('{')); // left brace (just after 'z')
        assertFalse(CharUtil.isUrlChar('^')); // caret (before 'a' range)
        assertFalse(CharUtil.isUrlChar('|')); // pipe (not in valid set)
    }

mvn test                       # Run tests
mvn formatter:format           # Format code
mvn license:format             # Update license headers
```

### Code Style

- 4 spaces (no tabs)
- Opening brace on same line
- Max line length: 120
- JavaDoc required for public APIs
- License headers required

### Testing

**Structure**: `src/test/java/org/codelibs/fess/crawler/`

    }

    /**
     * Creates a new CurlRequest with the HTTP TRACE method for the specified URL.
     *
     * @param url the URL to send the TRACE request to
     * @return a new CurlRequest object configured with the TRACE method and the specified URL
     */
    public static CurlRequest trace(final String url) {
        return new CurlRequest(Method.TRACE, url);
    }

    /**

        sb.append(",").append(appTypeSupplier.supply()).append(",").append(resource.getModuleName());
        final String trace = sb.toString();
        final int columnSize = 200;
        return trace.length() > columnSize ? trace.substring(0, columnSize) : trace;
    }

        for (final Entry<String, Map<String, CacheEntry<DfsReferralDataInternal>>> entry : domains.entrySet()) {
            log.trace("Domain " + entry.getKey());
            for (final Entry<String, CacheEntry<DfsReferralDataInternal>> entry2 : entry.getValue().entrySet()) {
                log.trace("  Root " + entry2.getKey());
                if (entry2.getValue().map != null) {

        String message1 = "Test with suppression enabled";
        CrawlerSystemException exception1 = constructor.newInstance(message1, true, true);
        assertNotNull(exception1);
        assertEquals(message1, exception1.getMessage());
        assertNull(exception1.getCause());

        // Test with suppression disabled and writable stack trace

        // ## Note: There's no Curl.trace() factory method, but we can use the constructor ##

        // ## Act ##
        final CurlRequest request = new CurlRequest(Method.TRACE, "http://example.com");

        // ## Assert ##
        assertNotNull(request);
        assertEquals(Method.TRACE, request.method());
    }

    @Test
    public void test_MethodEnumValueOf() {

        this.macSigningKey = macSigningKey;
        this.signSequence = initialSequence;
        this.bypass = bypass;

        if (log.isTraceEnabled()) {
            log.trace("macSigningKey:");
            log.trace(Hexdump.toHexString(macSigningKey, 0, macSigningKey.length));
        }
    }

    /**
     * This constructor used to instance a SigningDigest object for

     * suppression enabled or disabled, and writable stack trace enabled or disabled.
     *
     * @param message the detail message.
     * @param enableSuppression whether or not suppression is enabled or disabled.
     * @param writableStackTrace whether or not the stack trace should be writable.
     */

    }

    /**
     * Constructs a new CrawlerSystemException with the specified detail message and controls suppression and stack trace writing.
     *
     * @param message the detail message
     * @param enableSuppression whether or not suppression is enabled
     * @param writableStackTrace whether or not the stack trace should be writable
     */