* creation and removal (including automatic removal of zeroes). If the modification of an
   * AtomicInteger results in zero, we compareAndSet the value to zero; if that succeeds, we remove
   * the entry from the Map. If another operation sees a zero in the map, it knows that the entry is
   * about to be removed, so this operation may remove it (often by replacing it with a new
   * AtomicInteger).
   */

   * creation and removal (including automatic removal of zeroes). If the modification of an
   * AtomicInteger results in zero, we compareAndSet the value to zero; if that succeeds, we remove
   * the entry from the Map. If another operation sees a zero in the map, it knows that the entry is
   * about to be removed, so this operation may remove it (often by replacing it with a new
   * AtomicInteger).
   */

      entrySet.remove(entryOf(2, 2));
      assertFalse(entrySet.remove(null));
      assertFalse(entrySet.remove(entryOf(1, 1)));
      assertFalse(entrySet.remove(entryOf(6, 6)));
      assertFalse(entrySet.removeAll(asList(null, entryOf(1, 1), entryOf(15, 15))));
      assertFalse(entrySet.retainAll(asList(null, entryOf(1, 1), entryOf(15, 15))));
      checkEmpty(entrySet);
      checkEmpty(cache);
    }
  }

      entrySet.remove(entryOf(2, 2));
      assertFalse(entrySet.remove(null));
      assertFalse(entrySet.remove(entryOf(1, 1)));
      assertFalse(entrySet.remove(entryOf(6, 6)));
      assertFalse(entrySet.removeAll(asList(null, entryOf(1, 1), entryOf(15, 15))));
      assertFalse(entrySet.retainAll(asList(null, entryOf(1, 1), entryOf(15, 15))));
      checkEmpty(entrySet);
      checkEmpty(cache);
    }
  }

   *
   * <p>This method refines {@link Collection#remove} to further specify that it <b>may not</b>
   * throw an exception in response to {@code element} being null or of the wrong type.
   *
   * <p>To both remove the element and obtain the previous count of that element, use {@link
   * #remove(Object, int) remove}{@code (element, 1)} instead.
   *
   * @param element the element to remove one occurrence of

    AtomicLong atomic = map.get(key);
    if (atomic == null) {
      return false;
    }

    long oldValue = atomic.get();
    if (oldValue != value) {
      return false;
    }

    if (oldValue == 0L || atomic.compareAndSet(oldValue, 0L)) {
      // only remove after setting to zero, to avoid concurrent updates
      map.remove(key, atomic);

   * removeFrom.removeIf(predicate)} instead.
   *
   * @param removeFrom the iterable to (potentially) remove elements from
   * @param predicate a predicate that determines whether an element should be removed
   * @return {@code true} if any elements were removed from the iterable
   * @throws UnsupportedOperationException if the iterable does not support {@code remove()}.
   * @since 2.0
   */

      }
    }
  }

  private void compareResultsForThisListOfStimuli() {
    int removes = Collections.frequency(Arrays.asList(stimuli), remove);
    if ((!features.contains(IteratorFeature.SUPPORTS_REMOVE) && removes > 1)
        || (stimuli.length >= 5 && removes > 2)) {
      // removes are the most expensive thing to test, since they often throw exceptions with stack

      }
    }
  }

  private void compareResultsForThisListOfStimuli() {
    int removes = Collections.frequency(Arrays.asList(stimuli), remove);
    if ((!features.contains(IteratorFeature.SUPPORTS_REMOVE) && removes > 1)
        || (stimuli.length >= 5 && removes > 2)) {
      // removes are the most expensive thing to test, since they often throw exceptions with stack

  }

  // retainAll(empty)

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmpty() {
    expectReturnsFalse(empty);
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmptyUnsupported() {