value = "${123}";
        assertEquals("numeric", ResourceUtil.resolve(value));

        // Test with underscores in property names
        System.setProperty("test_var", "underscore");
        value = "${test_var}";
        assertEquals("underscore", ResourceUtil.resolve(value));

        // Clean up test properties
        System.clearProperty("var1");
        System.clearProperty("var2");

 *
 * <p>If not all classes on the classpath should be covered, {@link #ignoreClasses} can be used to
 * exclude certain classes. As a special case, classes with an underscore in the name (like {@code
 * AutoValue_Foo}) can be excluded using <code>ignoreClasses({@link #UNDERSCORE_IN_NAME})</code>.
 *
 * <p>{@link #setDefault} allows subclasses to specify default values for types.
 *

            // Expected
        }

        // Test with build info
        System.setProperty("java.version", "17.0.2+8");
        assertEquals(17, JvmUtil.getJavaVersion());

        // Test with underscore separators in old format
        System.setProperty("java.version", "1.8.0_301");
        assertEquals(8, JvmUtil.getJavaVersion());
    }

    @Test
    public void test_getJavaVersion_variousFormats() {

 *
 * <p>If not all classes on the classpath should be covered, {@link #ignoreClasses} can be used to
 * exclude certain classes. As a special case, classes with an underscore in the name (like {@code
 * AutoValue_Foo}) can be excluded using <code>ignoreClasses({@link #UNDERSCORE_IN_NAME})</code>.
 *
 * <p>{@link #setDefault} allows subclasses to specify default values for types.
 *

        buf.append(Integer.toHexString(i >> 16 & 0xff));
        buf.append(Integer.toHexString(i >> 8 & 0xff));
        buf.append(Integer.toHexString(i & 0xff));
    }

    /**
     * Converts an underscore-separated string to camel case.
     * <p>
     * Usage example:
     * </p>
     *
     * <pre>
     * StringUtil.camelize("USER_ID")  = "UserId"
     * </pre>
     *
     * @param s

     * <p>ASCII characters in the part are expected to be valid per RFC 1035, with underscore also
     * being allowed due to widespread practice.
     */

    String asciiChars = CharMatcher.ascii().retainFrom(part);

    if (!PART_CHAR_MATCHER.matchesAllOf(asciiChars)) {
      return false;
    }

    // No initial or final dashes or underscores.

    if (DASH_MATCHER.matches(part.charAt(0))

Ancak `user-agent` gibi bir değişken adı Python'da geçersizdir.

Bu yüzden, default olarak `Header`, header'ları almak ve dokümante etmek için parametre adlarındaki underscore (`_`) karakterlerini hyphen (`-`) ile dönüştürür.

Ayrıca HTTP header'ları büyük/küçük harfe duyarlı değildir; dolayısıyla onları standart Python stiliyle (diğer adıyla "snake_case") tanımlayabilirsiniz.

	return b
}

// isSeparator reports whether the rune could mark a word boundary.
// TODO: update when package unicode captures more of the properties.
func isSeparator(r rune) bool {
	// ASCII alphanumerics and underscore are not separators
	if r <= 0x7F {
		switch {
		case '0' <= r && r <= '9':
			return false
		case 'a' <= r && r <= 'z':
			return false
		case 'A' <= r && r <= 'Z':
			return false
		case r == '_':

and <code>A</code> through <code>F</code> represent values 10 through 15.
</p>

<p>
For readability, an underscore character <code>_</code> may appear after
a base prefix or between successive digits; such underscores do not change
the literal's value.
</p>
<pre class="ebnf">
int_lit        = decimal_lit | binary_lit | octal_lit | hex_lit .

- Promoted `RelaxedDNSSearchValidation` to beta, allowing for Pod search domains to be a single dot "." or contain an underscore "_". ([#130128](https://github.com/kubernetes/kubernetes/pull/130128), [@adrianmoisey](https://github.com/adrianmoisey)) [SIG Apps and Network]