checkNotNull(filter);
    boolean changed = false;
    for (K key : keySet()) {
      while (true) {
        V value = get(key);
        if (value == null || !filter.test(key, value)) {
          break;
        } else if (LocalCache.this.remove(key, value)) {
          changed = true;
          break;
        }
      }
    }
    return changed;
  }

    // The composed future also yields 6.
    assertEquals(6, getDone(transformedFuture).intValue());

    // Repeated calls yield the same value even though the function's behavior
    // changes
    holder.value = 3;
    assertEquals(6, getDone(transformedFuture).intValue());
    assertEquals(7, adder.apply(4).intValue());

    // Once more, with feeling.
    holder.value = 4;

     * be read without locking. Next fields of nodes are immutable (final). All list additions are
     * performed at the front of each bin. This makes it easy to check changes, and also fast to
     * traverse. When nodes would otherwise be changed, new nodes are created to replace them. This
     * works well for hash tables since the bin lists tend to be short. (The average length is less
     * than two.)
     *

  }

  /**
   * Computes the difference between two maps. This difference is an immutable snapshot of the state
   * of the maps at the time this method is called. It will never change, even if the maps change at
   * a later time.
   *
   * <p>Since this method uses {@code HashMap} instances internally, the keys of the supplied maps

    // The composed future also yields 6.
    assertEquals(6, getDone(transformedFuture).intValue());

    // Repeated calls yield the same value even though the function's behavior
    // changes
    holder.value = 3;
    assertEquals(6, getDone(transformedFuture).intValue());
    assertEquals(7, adder.apply(4).intValue());

    // Once more, with feeling.
    holder.value = 4;