assertEquals("UTF-8", encodingHelper.normalize(enc));

        enc = "Shift_JIS";
        assertEquals("Shift_JIS", encodingHelper.normalize(enc));

        enc = "S-JIS";
        assertEquals("Shift_JIS", encodingHelper.normalize(enc));
    }

    public void test_normalize_null() {
        String enc;

        enc = null;
        assertNull(encodingHelper.normalize(enc));

        enc = "";

<!DOCTYPE components PUBLIC "-//DBFLUTE//DTD LastaDi 1.0//EN"
	"http://dbflute.org/meta/lastadi10.dtd">
<components namespace="fessCrawler">
	<include path="crawler/container.xml" />

	<!-- Converts child links to normalize it. -->
	<component name="urlConvertHelper" class="org.codelibs.fess.crawler.helper.UrlConvertHelper">
	</component>

        // Default constructor
    }

    /**
     * Normalizes an encoding string to its preferred form.
     *
     * @param enc the encoding string to normalize
     * @return the normalized encoding or the default encoding if the input is blank
     */
    public String normalize(final String enc) {
        if (StringUtil.isBlank(enc)) {
            return defaultEncoding;
        }

 * It uses the Apache Tika library to detect the MIME type.
 *
 * <p>
 * This class provides methods to:
 * </p>
 * <ul>
 *   <li>Detect the MIME type based on the input stream and filename.</li>
 *   <li>Normalize the filename to handle special characters.</li>
 *   <li>Configure whether to use the filename for MIME type detection.</li>
 *   <li>Configure whether to use the filename for MIME type detection when the stream is octet-stream.</li>