synchronized (mutex) {
        return map(delegate().row(rowKey), mutex);
      }
    }

    @Override
    public Map<R, V> column(@ParametricNullness C columnKey) {
      synchronized (mutex) {
        return map(delegate().column(columnKey), mutex);
      }
    }

    @Override
    public Set<Cell<R, C, V>> cellSet() {
      synchronized (mutex) {

        ExecutorService createExecutor(int parallelism) {
            //
            // We need an executor that will not block.
            // We can't use work stealing, as we are building a graph
            // and this could lead to cycles where a thread waits for
            // a task to finish, then execute another one which waits
            // for the initial task...
            // In order to work around that problem, we override the

        .isEqualTo(initialBuckets);

    // Ensure that referenceMap, which doesn't use WithExpectedSize, ends up with the same table
    // size as the other two maps. If it ended up with a smaller size that would imply that we
    // computed the wrong initial capacity.
    for (int i = 0; i < size; i++) {
      referenceMap.put(i, null);
    }
    assertWithMessage("table size after adding " + size + " elements")

        .isEqualTo(initialBuckets);

    // Ensure that referenceMap, which doesn't use WithExpectedSize, ends up with the same table
    // size as the other two maps. If it ended up with a smaller size that would imply that we
    // computed the wrong initial capacity.
    for (int i = 0; i < size; i++) {
      referenceMap.put(i, null);
    }
    assertWithMessage("table size after adding " + size + " elements")

    throw new InvalidObjectException("Use SerializedForm");
  }

  // This class is never actually serialized directly, but we have to make the
  // warning go away (and suppressing would suppress for all nested classes too)
  private static final long serialVersionUID = 0;

  /**
   * Not supported. Use {@link #toImmutableSortedMap}, which offers better type-safety, instead.

      public void run() {
        cache.refresh(refreshKey);
        getFinishedSignal.countDown();
      }
    }.start();

    getStartedSignal.await();

    // computation is in progress; asMap shouldn't have changed
    assertEquals(1, map.size());
    assertFalse(map.containsKey(getKey));
    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete
    letGetFinishSignal.countDown();

  /**
   * The elements in this map would pass the UNDER test, but are known not to be public suffixes and
   * are thus excluded from consideration. Since it refers to elements in UNDER of the same type,

  //    (hypothetical) unsafe read by our caller. Note: adding 'volatile' does not fix this issue,
  //    it would just add an edge such that if done() observed non-null, then it would also
  //    definitely observe all earlier writes, but we still have no guarantee that done() would see
  //    the initial write (just stronger guarantees if it does).
  //

   * passing a TypeToken<X>. This would be invalid. Maybe we could accept a TypeParameter<@PolyNull
   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.
   *

    assertFalse(
        from.getType() + " shouldn't be assignable to " + to.getType(), to.isSupertypeOf(from));
    assertFalse(
        to.getType() + " shouldn't be a supertype of " + from.getType(), to.isSupertypeOf(from));
    assertFalse(
        from.getType() + " shouldn't be a subtype of " + to.getType(), from.isSubtypeOf(to));
  }