* @throws ArrayStoreException if the runtime type of the specified array is not a supertype of
   *     the runtime type of every element in the specified collection
   */
  static <T extends @Nullable Object> T[] toArrayImpl(Collection<?> c, T[] array) {
    int size = c.size();
    if (array.length < size) {
      array = newArray(array, size);
    }
    fillArray(c, array);
    if (array.length > size) {

   * @throws ArrayStoreException if the runtime type of the specified array is not a supertype of
   *     the runtime type of every element in the specified collection
   */
  static <T extends @Nullable Object> T[] toArrayImpl(Collection<?> c, T[] array) {
    int size = c.size();
    if (array.length < size) {
      array = newArray(array, size);
    }
    fillArray(c, array);
    if (array.length > size) {

    doTestToArrayImpl1(Lists.<@Nullable Integer>newArrayList(1, null, 3));
  }

  private void doTestToArrayImpl1(List<Integer> list) {
    Object[] reference = list.toArray();
    Object[] target = ObjectArrays.toArrayImpl(list);
    assertEquals(reference.getClass(), target.getClass());
    assertTrue(Arrays.equals(reference, target));
  }

  public void testToArrayImpl2() {

  public Object[] toArray() {
    /*
     * ObjectArrays.toArrayImpl returns `@Nullable Object[]` rather than `Object[]` but only because
     * it can be used with collections that may contain null. This collection is a collection of
     * non-null elements, so we can treat it as a plain `Object[]`.
     */
    @SuppressWarnings("nullness")
    Object[] result = ObjectArrays.toArrayImpl(this);
    return result;
  }

  @Override

  }

  @Override
  public @Nullable Object[] toArray() {
    return ObjectArrays.toArrayImpl(this);
  }

  @Override
  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
  public <T extends @Nullable Object> T[] toArray(T[] a) {
    return ObjectArrays.toArrayImpl(this, a);
  }

  @Override
  public void clear() {
    if (needsAllocArrays()) {

        }
        return a;
      }
      Map<K, V> delegate = delegateOrNull();
      return (delegate != null)
          ? delegate.keySet().toArray(a)
          : ObjectArrays.toArrayImpl(requireKeys(), 0, size, a);
    }

    @Override
    public boolean remove(@Nullable Object o) {
      Map<K, V> delegate = delegateOrNull();
      return (delegate != null)

      if (a.length > 0) {
        a[0] = null;
      }
      return a;
    }
    Set<E> delegate = delegateOrNull();
    return (delegate != null)
        ? delegate.toArray(a)
        : ObjectArrays.toArrayImpl(requireElements(), 0, size, a);
  }

  /**
   * Ensures that this {@code CompactHashSet} has the smallest representation in memory, given its
   * current size.
   */
  public void trimToSize() {