final Date date = toDate("10/9/7");
        assertThat(new SimpleDateFormat("yyyy/MM/dd").format(date), is("2010/09/07"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testToDate_MediumStyle() throws Exception {
        final Date date = toDate("2010/9/7");
        assertThat(new SimpleDateFormat("yyyy/MM/dd").format(date), is("2010/09/07"));
    }

    /**
     * @throws Exception

    "EEE, dd MMM yyyy HH:mm:ss zzz",
    // RFC 850, obsoleted by RFC 1036 with any TZ.
    "EEEE, dd-MMM-yy HH:mm:ss zzz",
    // ANSI C's asctime() format
    "EEE MMM d HH:mm:ss yyyy",
    // Alternative formats:
    "EEE, dd-MMM-yyyy HH:mm:ss z",
    "EEE, dd-MMM-yyyy HH-mm-ss z",
    "EEE, dd MMM yy HH:mm:ss z",
    "EEE dd-MMM-yyyy HH:mm:ss z",
    "EEE dd MMM yyyy HH:mm:ss z",
    "EEE dd-MMM-yyyy HH-mm-ss z",

        assertThat(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(date), is("2010/09/07 11:49:00"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testToDate_MediumStyle() throws Exception {
        final Date date = toDate("2010/9/7 11:49:10", Locale.JAPAN);
        assertThat(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(date), is("2010/09/07 11:49:10"));
    }

    /**
     * ISO 8601 extended format: yyyy-MM-dd'T'HH:mm:ss.SSSZ
     */
    public static final String DATE_FORMAT_ISO_8601_EXTEND = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";

    /**
     * ISO 8601 extended UTC format: yyyy-MM-dd'T'HH:mm:ss.SSS'Z'
     */
    public static final String DATE_FORMAT_ISO_8601_EXTEND_UTC = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

    /**
     * Digit only date format: yyyyMMddHHmmss

public class TimestampConverterTest {

    /**
     * @throws Exception
     */
    @Test
    public void testGetAsObjectAndGetAsString() throws Exception {
        final TimestampConverter converter = new TimestampConverter("yyyy/MM/dd HH:mm:ss");
        final java.sql.Timestamp result = (java.sql.Timestamp) converter.getAsObject("2008/12/31 12:34:56");
        System.out.println(result);

 */
public class DateConverterTest {

    /**
     * @throws Exception
     */
    @Test
    public void testGetAsObjectAndGetAsString() throws Exception {
        final DateConverter converter = new DateConverter("yyyy/MM/dd");
        final Date result = (Date) converter.getAsObject("2008/01/16");
        System.out.println(result);
        assertThat(converter.getAsString(result), is("2008/01/16"));
    }

    /**

public class SqlDateConverterTest {

    /**
     * @throws Exception
     */
    @Test
    public void testGetAsObjectAndGetAsString() throws Exception {
        final SqlDateConverter converter = new SqlDateConverter("yyyy/MM/dd");
        final java.sql.Date result = (java.sql.Date) converter.getAsObject("2008/01/16");
        System.out.println(result);
        assertThat(converter.getAsString(result), is("2008/01/16"));
    }

    /**

    <function-class>org.codelibs.fess.taglib.FessFunctions</function-class>
    <function-signature>java.util.Date parseDate(java.lang.String, java.lang.String)</function-signature>
    <example>
      ${fe:parseDate(doc.tstamp, "yyyy-MM-dd HH:mm:ss")}
    </example>
  </function>

  <function>
    <description>
      Returns formatted duration from a given value.
    </description>
    <name>formatDuration</name>

				</div>
				<div class="info">
					<fmt:formatDate value="${fe:parseDate(doc.last_modified)}" type="BOTH" pattern="yyyy-MM-dd HH:mm" />
					<c:if test="${doc.last_modified==null || doc.last_modified==''}">
						<fmt:formatDate value="${fe:parseDate(doc.created)}" type="BOTH" pattern="yyyy-MM-dd HH:mm" />
					</c:if>
					<c:if test="${doc.content_length!=null && doc.content_length!=''}">
						<div class="d-sm-none"></div>

Integer nullValue = IntegerConversionUtil.toInteger(null);     // Returns null
Boolean flag = BooleanConversionUtil.toBoolean("true");        // Returns true
Date date = DateConversionUtil.toDate("2023-12-25", "yyyy-MM-dd");

// Primitive conversions with default values
int primitiveInt = IntegerConversionUtil.toPrimitiveInt(value, "0");  // Default to 0 if null
```

### Collection Utilities with Java 21 Support
```java