* find it when available. When this is null, use the slow way.
   */
  @J2ktIncompatible
  @GwtIncompatible // java.lang.reflect
  @CheckForNull
  private static final Method getStackTraceElementMethod = (jla == null) ? null : getGetMethod();

  /**
   * The "getStackTraceDepth" method, only available on some JDKs so we use reflection to find it
   * when available. When this is null, use the slow way.
   */

   * find it when available. When this is null, use the slow way.
   */
  @J2ktIncompatible
  @GwtIncompatible // java.lang.reflect
  @CheckForNull
  private static final Method getStackTraceElementMethod = (jla == null) ? null : getGetMethod();

  /**
   * The "getStackTraceDepth" method, only available on some JDKs so we use reflection to find it
   * when available. When this is null, use the slow way.
   */

       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
       * worth noting that we promise not to put nulls into the array in the first `size` elements.
       * We uphold that promise here because our callers promise that `elements` will not contain
       * nulls in its first `n` elements.
       */
      System.arraycopy(elements, 0, contents, size, n);
      size += n;

        TreeMultimap.create(StringLength.COMPARATOR, DECREASING_INT_COMPARATOR);
    multimap.put("google", 2);
    multimap.put("google", 6);
    multimap.put(null, 3);
    multimap.put(null, 1);
    multimap.put(null, 7);
    multimap.put("tree", 0);
    multimap.put("tree", null);
    return multimap;
  }

  /** Test that a TreeMultimap created from another uses the natural ordering. */

        current.elemCount = 0;
        // Also clear these fields so that one deleted Entry doesn't retain all elements.
        current.left = null;
        current.right = null;
        current.pred = null;
        current.succ = null;

        current = next;
      }
      successor(header, header);
      rootReference.clear();
    } else {

    Predicate<@Nullable Integer> isNull = Predicates.equalTo(null);
    assertTrue(isNull.apply(null));
    assertFalse(isNull.apply(1));
  }

  public void testIsEqualToNull_equality() {
    new EqualsTester()
        .addEqualityGroup(
            Predicates.<@Nullable Integer>equalTo(null),
            Predicates.<@Nullable Integer>equalTo(null))
        .addEqualityGroup(Predicates.equalTo(1))

  @CollectionFeature.Require({SUPPORTS_ADD, ALLOWS_NULL_VALUES})
  public void testOffer_nullSupported() {
    assertTrue("offer(null) should return true", getQueue().offer(null));
    expectAdded((E) null);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testOffer_nullUnsupported() {
    try {
      getQueue().offer(null);
      fail("offer(null) should throw");

      return;
    }

    map.put(null, unmappedValue);
    assertEquals(unmappedValue, map.get(null));
    assertTrue(map.containsKey(null));
    Entry<@Nullable K, V> entry = mapEntry(null, unmappedValue);
    assertTrue(entrySet.remove(entry));
    assertNull(map.get(null));
    assertFalse(map.containsKey(null));
  }

  public void testEntrySetRemoveNullKeyMissing() {

      cachingHashMap.remove(key);
      return null;
    }
  }

  @CanIgnoreReturnValue
  @Override
  public V put(K key, V value) {
    checkNotNull(key);
    checkNotNull(value);
    Timestamped<V> oldValue = cachingHashMap.put(key, new Timestamped<V>(value, ticker));
    if (oldValue == null) {
      return null;
    }

    int[] expected = {0, 1, 2, 1, 4, 5, 0};
    checkIndexOf(toTest, expected);
  }

  public void testIndexOfImpl_null() {
    List<String> toTest;
    try {
      toTest = createList(String.class, null, "A", "B", null, "C", null);
    } catch (NullPointerException e) {
      // example cannot handle nulls, test invalid
      return;
    }
    int[] expected = {0, 1, 2, 0, 4, 0};
    checkIndexOf(toTest, expected);
  }