*
   * @return {@code first} if it is non-null; otherwise {@code second} if it is non-null
   * @throws NullPointerException if both {@code first} and {@code second} are null
   * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }

            }
          },
          "mappings": [],
          "thresholds": {
            "mode": "absolute",
            "steps": [
              {
                "color": "green",
                "value": null
              },
              {
                "color": "red",
                "value": 80
              }
            ]
          },
          "unit": "short"
        },
        "overrides": [

    }

    @Test
    @DisplayName("openConnection with null URL throws NullPointerException")
    void testOpenConnection_NullInput() {
        // Arrange
        Handler handler = newHandlerWith(mockCtx);

        // Act & Assert
        assertThrows(NullPointerException.class, () -> handler.openConnection(null), "Null URL should throw NPE");

@GwtCompatible
final class CollectPreconditions {

  static void checkEntryNotNull(Object key, Object value) {
    if (key == null) {
      throw new NullPointerException("null key in entry: null=" + value);
    } else if (value == null) {
      throw new NullPointerException("null value in entry: " + key + "=null");
    }
  }

  @CanIgnoreReturnValue
  static int checkNonnegative(int value, String name) {
    if (value < 0) {

   *
   * @throws NullPointerException if the element is null
   * @since 6.0 (source-compatible since 2.0)
   */
  public static <E> ImmutableMultiset<E> of(E e1) {
    return copyFromElements(e1);
  }

  /**
   * Returns an immutable multiset containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   * @since 6.0 (source-compatible since 2.0)
   */

        verify(messageBlock).getDigest();
    }

    @Test
    @DisplayName("Test setDigest with null value")
    void testSetDigestWithNull() {
        // Given
        doNothing().when(messageBlock).setDigest(null);
        when(messageBlock.getDigest()).thenReturn(null);

        // When
        messageBlock.setDigest(null);
        SMBSigningDigest retrievedDigest = messageBlock.getDigest();

        // Then

  private val key: String

  /** Non-null for client web sockets. These can be canceled. */
  internal var call: Call? = null

  /** This task processes the outgoing queues. Call [runWriter] to after enqueueing. */
  private var writerTask: Task? = null

  /** Null until this web socket is connected. Only accessed by the reader thread. */
  private var reader: WebSocketReader? = null

   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {

                }));
    expectReplacement(entry(getKeyForNullValue(), v3()));
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  public void testMergeAbsentNullKey() {
    assertEquals(
        "Map.merge(null, value, function) should return value",
        v3(),
        getMap()
            .merge(
                null,
                v3(),

        .build(),
    )
    val source = newEventSource()
    assertThat(source.request().url.encodedPath).isEqualTo("/")
    listener.assertOpen()
    listener.assertEvent(null, null, "hey")
    listener.assertClose()
  }

  @RetryingTest(5)
  fun cancelInEventShortCircuits() {
    server.enqueue(
      MockResponse
        .Builder()
        .body(
          """