*/
package org.codelibs.core.beans.util;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.not;
import static org.hamcrest.CoreMatchers.nullValue;
import static org.hamcrest.CoreMatchers.sameInstance;
import static org.junit.Assert.assertThat;

import java.sql.Time;
import java.sql.Timestamp;
import java.util.Date;

 */
package org.codelibs.core.beans.impl;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.notNullValue;
import static org.hamcrest.CoreMatchers.nullValue;
import static org.hamcrest.CoreMatchers.sameInstance;
import static org.junit.Assert.assertThat;

import java.lang.reflect.Constructor;

import org.codelibs.core.beans.BeanDesc;

        assertEquals("present", presentOptional.get());
        assertEquals("present", presentOptional.orElse("default"));

        // Test with null value
        String nullValue = null;
        OptionalEntity<String> emptyOptional = OptionalUtil.ofNullable(nullValue);

        assertFalse(emptyOptional.isPresent());
        assertEquals("default", emptyOptional.orElse("default"));

 * governing permissions and limitations under the License.
 */
package org.codelibs.core.lang;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.nullValue;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertThat;

import org.junit.Test;

/**
 * @author wyukawa
 *
 */
public class ObjectUtilTest {

    /**

 */
package org.codelibs.core.lang;

import static org.codelibs.core.TestUtil.sameClass;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.nullValue;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;

import java.lang.reflect.Field;
import java.util.Collection;
import java.util.Map;

        () -> ImmutableBiMap.ofEntries((Entry<Integer, Integer>) nullKey));
    Entry<Integer, @Nullable Integer> nullValue =
        ImmutableBiMapTest.<@Nullable Integer>entry(23, null);
    assertThrows(
        NullPointerException.class,
        () -> ImmutableBiMap.ofEntries((Entry<Integer, Integer>) nullValue));
  }

  private static <T extends @Nullable Object> Entry<T, T> entry(T key, T value) {

    boolean nullKeys = inverseFeatures.remove(MapFeature.ALLOWS_NULL_KEYS);
    boolean nullValues = inverseFeatures.remove(MapFeature.ALLOWS_NULL_VALUES);

    if (nullKeys) {
      inverseFeatures.add(MapFeature.ALLOWS_NULL_VALUES);
    }
    if (nullValues) {
      inverseFeatures.add(MapFeature.ALLOWS_NULL_KEYS);
    }

    inverseFeatures.add(NoRecurse.INVERSE);

```

### Type Conversion
```java
import org.codelibs.core.convert.*;

// Safe type conversions with null handling
Integer value = IntegerConversionUtil.toInteger("123");        // Returns 123
Integer nullValue = IntegerConversionUtil.toInteger(null);     // Returns null
Boolean flag = BooleanConversionUtil.toBoolean("true");        // Returns true
Date date = DateConversionUtil.toDate("2023-12-25", "yyyy-MM-dd");

    // null key
    InternalEntry<Object, Object, ?> nullEntry = segment.newEntryForTesting(null, hash, entry);
    Object nullValue = new Object();
    WeakValueReference<Object, Object, ?> nullValueRef =
        segment.newWeakValueReferenceForTesting(nullEntry, nullValue);
    segment.setWeakValueReferenceForTesting(nullEntry, nullValueRef);
    segment.setTableEntryForTesting(index, nullEntry);
    // skip the null key

    // null key
    InternalEntry<Object, Object, ?> nullEntry = segment.newEntryForTesting(null, hash, entry);
    Object nullValue = new Object();
    WeakValueReference<Object, Object, ?> nullValueRef =
        segment.newWeakValueReferenceForTesting(nullEntry, nullValue);
    segment.setWeakValueReferenceForTesting(nullEntry, nullValueRef);
    segment.setTableEntryForTesting(index, nullEntry);
    // skip the null key