*
   * <p><b>Discouraged:</b> Prefer using either {@code x -> x == null} or {@code Objects::isNull},
   * but note that lambdas and method references do not have human-readable {@link #toString()}
   * representations and are not serializable.
   */
  public static <T extends @Nullable Object> Predicate<T> isNull() {
    return ObjectPredicate.IS_NULL.withNarrowedType();
  }

  /**

   *
   * <p><b>Discouraged:</b> Prefer using either {@code x -> x == null} or {@code Objects::isNull},
   * but note that lambdas and method references do not have human-readable {@link #toString()}
   * representations and are not serializable.
   */
  public static <T extends @Nullable Object> Predicate<T> isNull() {
    return ObjectPredicate.IS_NULL.withNarrowedType();
  }

  /**

  private static final Object OBJECT = new Object();

  public void testNewReference() throws Exception {
    assertThat(Atomics.newReference().get()).isNull();
  }

  public void testNewReference_withInitialValue() throws Exception {
    assertThat(Atomics.newReference(null).get()).isNull();
    assertEquals(OBJECT, Atomics.newReference(OBJECT).get());
  }

  public void testNewReferenceArray_withLength() throws Exception {

    assertThat(map.get(Integer.class)).isNull();
    assertThat(map.getInstance(Integer.class)).isNull();

    map.put(Long.class, null);
    assertThat(map.get(Long.class)).isNull();
    assertThat(map.getInstance(Long.class)).isNull();
  }

  public void testPrimitiveAndWrapper() {
    assertThat(map.getInstance(int.class)).isNull();
    assertThat(map.getInstance(Integer.class)).isNull();

    // On Windows files still exist while being edited.
    assertThat(readFileOrNull(getCleanFile("k1", 0))).isEqualTo(afterRemoveFileContents)
    assertThat(readFileOrNull(getDirtyFile("k1", 0))).isNull()

    // On all platforms files are deleted when the edit completes.
    editor.commit()
    assertThat(readFileOrNull(getCleanFile("k1", 0))).isNull()
    assertThat(readFileOrNull(getDirtyFile("k1", 0))).isNull()

        .url("https://square.com")
        .build()
    assertThat(request.tag<Any>()).isNull()
    assertThat(request.tag(Any::class)).isNull()
    assertThat(request.tag(String::class)).isNull()

    // Alternate access APIs also work.
    assertThat(request.tag<String>()).isNull()
    assertThat(request.tag(String::class)).isNull()
  }

  @Test
  fun defaultTag() {
    val tag = "1234"
    val request =

        .build()
    assertThat(request.tag()).isNull()
    assertThat(request.tag(Any::class.java)).isNull()
    assertThat(request.tag(UUID::class.java)).isNull()
    assertThat(request.tag(String::class.java)).isNull()

    // Alternate access APIs also work.
    assertThat(request.tag<String>()).isNull()
    assertThat(request.tag(String::class)).isNull()
  }

  @Test
  fun defaultTag() {

    segment.setValueForTesting(entry, value);

    assertThat(segment.get(key, hash)).isNull();

    // count == 0
    segment.setTableEntryForTesting(index, entry);
    assertThat(segment.get(key, hash)).isNull();
    assertFalse(segment.containsKey(key, hash));
    assertFalse(segment.containsValue(value));

    // count == 1
    segment.count++;

    segment.setValueForTesting(entry, value);

    assertThat(segment.get(key, hash)).isNull();

    // count == 0
    segment.setTableEntryForTesting(index, entry);
    assertThat(segment.get(key, hash)).isNull();
    assertFalse(segment.containsKey(key, hash));
    assertFalse(segment.containsValue(value));

    // count == 1
    segment.count++;

    assertEquals(TestEnum.HONDA, converter.convert("HONDA"));
    assertEquals(TestEnum.POODLE, converter.convert("POODLE"));
    assertThat(converter.convert(null)).isNull();
    assertThat(converter.reverse().convert(null)).isNull();
  }

  public void testStringConverter_convertError() {
    Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);