* 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.
   */

  private <T extends Iterator<E>> void internalExecuteAndCompare(
      T reference, T target, IteratorOperation method) {
    Object referenceReturnValue = null;
    PermittedMetaException referenceException = null;
    Object targetReturnValue = null;
    Exception targetException = null;

    try {
      targetReturnValue = method.execute(target);
    } catch (Exception e) { // sneaky checked exception
      targetException = e;

     */
    if (result == null) {
      return null;
    } else {
      return (V) result;
    }
  }

  @CheckForNull
  static Object get(
      @CheckForNull Object hashTableObject,
      @Nullable Object[] alternatingKeysAndValues,
      int size,
      int keyOffset,
      @CheckForNull Object key) {
    if (key == null) {
      return null;
    } else if (size == 1) {

    if (entry == null) {
      return null;
    } else {
      delete(entry);
      entry.prevInKeyInsertionOrder = null;
      entry.nextInKeyInsertionOrder = null;
      return entry.value;
    }
  }

  @Override
  public void clear() {
    size = 0;
    Arrays.fill(hashTableKToV, null);
    Arrays.fill(hashTableVToK, null);
    firstInKeyInsertionOrder = null;

  private static final Iterable<@Nullable Integer> ITERABLE_NULL = Arrays.asList((Integer) null);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL_NULL =
      Arrays.asList((Integer) null, null);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL_1 = Arrays.asList(null, 1);
  private static final Iterable<@Nullable Integer> ITERABLE_1_NULL = Arrays.asList(1, null);

        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 {

      int size = (keyList == null) ? 0 : keyList.count;
      checkPositionIndex(index, size);
      if (index >= (size / 2)) {
        previous = (keyList == null) ? null : keyList.tail;
        nextIndex = size;
        while (index++ < size) {
          previous();
        }
      } else {
        next = (keyList == null) ? null : keyList.head;
        while (index-- > 0) {
          next();

      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;
    }