new AbstractLoadingCache<Object, Object>() {
          @Override
          public Object get(Object key) throws ExecutionException {
            Object v = valueRef.get();
            if (v == null) {
              throw new ExecutionException(cause);
            }
            return v;
          }

          @Override
          public @Nullable Object getIfPresent(Object key) {

  /**
   * The collection must not throw {@code NullPointerException} on calls such as {@code
   * contains(null)} or {@code remove(null)}, but instead must return a simple {@code false}.
   */
  ALLOWS_NULL_QUERIES,
  ALLOWS_NULL_VALUES(ALLOWS_NULL_QUERIES),

  /**
   * Indicates that a collection disallows certain elements (other than {@code null}, whose validity

            public String findTool(String toolName) {
                return null;
            }
        };
    }

    private DefaultToolchain newDefaultToolchain(ToolchainModel model, String type) {
        return new DefaultToolchain(model, type, logger) {
            @Override
            public String findTool(String toolName) {
                return null;
            }
        };
    }

    @Test

        Thread th = new Thread(() -> {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException ignore) {}
            deferred.resolve(new SuggestResponse("", 0, Collections.emptyList(), 0, null));
        });
        th.start();

        final CountDownLatch latch = new CountDownLatch(1);
        deferred.promise().then(response -> latch.countDown());
        assertTrue(latch.await(10, TimeUnit.SECONDS));

        assertEquals("b", result[1]);
        assertEquals("c", result[2]);
    }

    public void test_distinct_withNullElements() {
        // Test distinct with null elements
        String[] input = new String[] { "a", null, "b", null, "a" };
        String[] result = invokeDistinct(input);
        assertEquals(3, result.length);
        assertEquals("a", result[0]);
        assertNull(result[1]);

                wConfig.setAvailable(Constants.T);
                wConfig.setBoost(1.0f);
                wConfig.setCreatedBy(username);
                wConfig.setCreatedTime(now);
                if (form.depth != null) {
                    wConfig.setDepth(form.depth);
                }
                wConfig.setExcludedDocUrls(getDefaultString("default.config.web.excludedDocUrls", StringUtil.EMPTY));

    return (connectingEdge == null)
        ? ImmutableSet.<E>of().iterator()
        : Iterators.singletonIterator(connectingEdge);
  }

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

  @Override
  public boolean contains(@Nullable Object edge) {
    E connectingEdge = getConnectingEdge();
    return connectingEdge != null && connectingEdge.equals(edge);
  }

     * .
     */
    @Test
    public void testCreateAndCopySrcNull() {
        exception.expect(NullArgumentException.class);
        exception.expectMessage(is("[ECL0008]argument[calendar] is null."));
        CalendarConversionUtil.localize(null);
    }

    }

    @Test
    @DisplayName("Should handle null preauth integrity for SMB 3.0.0")
    void testDeriveKeys_NullPreauthForSMB300() {
        // Given
        int dialect = Smb2Constants.SMB2_DIALECT_0300;

        // When - SMB 3.0.0 doesn't use preauth integrity, so null should be acceptable
        byte[] signingKey = Smb3KeyDerivation.deriveSigningKey(dialect, sessionKey, null);

        // Then

     */
    Class<?> getValueClassOfMap(int index);

    /**
     * Returns the element type if the return type of the method is a parameterized {@link Collection}.
     *
     * @return the element type if the return type of the method is a parameterized {@link Collection}, otherwise {@literal null}
     */
    Class<?> getElementClassOfCollection();