*
   * <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();
  }

  /**

	}
	// check empty or full
	if rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is false but got true")
	}
	if rb.IsFull() {
		t.Fatalf("expect IsFull is false but got true")
	}

	// write to, isFull
	err = rb.WriteByte('b')
	if err != nil {
		t.Fatalf("WriteByte failed: %v", err)
	}
	if rb.Length() != 2 {

    assertThat(parse(url, "a\u0000b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0000d")).isNull()
    assertThat(parse(url, "a\u0001b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0001d")).isNull()
    assertThat(parse(url, "a\u0009b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0009d")).isNull()
    assertThat(parse(url, "a\u001fb=cd")).isNull()
    assertThat(parse(url, "ab=c\u001fd")).isNull()

    assertThat(spec.initialCapacity).isNull();
    assertThat(spec.maximumSize).isNull();
    assertThat(spec.maximumWeight).isNull();
    assertThat(spec.concurrencyLevel).isNull();
    assertThat(spec.keyStrength).isNull();
    assertThat(spec.valueStrength).isNull();
    assertThat(spec.writeExpirationTimeUnit).isNull();
    assertThat(spec.accessExpirationTimeUnit).isNull();

  }

  public void testHigherEntry() {
    assertThat(create().higherEntry("a")).isNull();
  }

  public void testHigherKey() {
    assertThat(create().higherKey("a")).isNull();
  }

  public void testLastEntry() {
    assertThat(create().lastEntry()).isNull();
  }

  public void testLastKey() {
    NavigableMap<String, Integer> map = create();
    map.put("a", 1);

    assertThat(Ints.tryParse("")).isNull();
    assertThat(Ints.tryParse("-")).isNull();
    assertThat(Ints.tryParse("+1")).isNull();
    assertThat(Ints.tryParse("9999999999999999")).isNull();
    assertWithMessage("Max integer + 1")
        .that(Ints.tryParse(Long.toString(((long) GREATEST) + 1)))
        .isNull();
    assertWithMessage("Max integer * 10")

        .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 =

        boundary = "simple boundary",
        source = Buffer().writeUtf8(multipart),
      )

    assertThat(parts.nextPart()).isNotNull()
    assertThat(parts.nextPart()).isNull()
    assertThat(parts.nextPart()).isNull()
  }

  @Test fun `empty source`() {
    val parts =
      MultipartReader(
        boundary = "simple boundary",
        source = Buffer(),
      )

        .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() {