* already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because
  // RemovalNotification is guaranteed covariant, let's make users' lives simpler.
  void onRemoval(RemovalNotification<K, V> notification);

  }

  @Override
  public N adjacentNode(E edge) {
    // Since the reference node is defined to be 'source' for directed graphs,
    // we can assume this edge lives in the set of outgoing edges.
    // (We're relying on callers to call this method only with an edge that's in the graph.)
    return requireNonNull(outEdgeMap.get(edge));
  }

  @Override

  /*
   * Arrays are a mess from a nullness perspective, and Class instances for object-array types are
   * even worse. For now, we just suppress and move on with our lives.
   *
   * - https://github.com/jspecify/jspecify/issues/65
   *
   * - https://github.com/jspecify/jdk/commit/71d826792b8c7ef95d492c50a274deab938f2552
   */
  /*

   * already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because
  // RemovalNotification is guaranteed covariant, let's make users' lives simpler.
  void onRemoval(RemovalNotification<K, V> notification);

   *
   * @see Collections#frequency
   */
  public static int frequency(Iterator<?> iterator, @CheckForNull Object element) {
    int count = 0;
    while (contains(iterator, element)) {
      // Since it lives in the same class, we know contains gets to the element and then stops,
      // though that isn't currently publicly documented.
      count++;
    }
    return count;
  }

  /**

   *
   * @see Collections#frequency
   */
  public static int frequency(Iterator<?> iterator, @CheckForNull Object element) {
    int count = 0;
    while (contains(iterator, element)) {
      // Since it lives in the same class, we know contains gets to the element and then stops,
      // though that isn't currently publicly documented.
      count++;
    }
    return count;
  }

  /**

    TestCharSource lines = new TestCharSource(LINES);
    assertEquals("foo", lines.readFirstLine());
    assertTrue(lines.wasStreamOpened() && lines.wasStreamClosed());
  }

  public void testReadLines_toList() throws IOException {
    TestCharSource lines = new TestCharSource(LINES);
    assertEquals(ImmutableList.of("foo", "bar", "baz", "something"), lines.readLines());

   * scattered in memory and thus don't interfere much with each
   * other. But Atomic objects residing in arrays will tend to be
   * placed adjacent to each other, and so will most often share
   * cache lines (with a huge negative performance impact) without
   * this precaution.
   *
   * In part because Cells are relatively large, we avoid creating
   * them until they are needed.  When there is no contention, all

      return lines.hasNext() ? lines.next() : null;
    }

    @Override
    public ImmutableList<String> readLines() {
      return ImmutableList.copyOf(linesIterator());
    }

    @Override
    @ParametricNullness
    public <T extends @Nullable Object> T readLines(LineProcessor<T> processor) throws IOException {
      Iterator<String> lines = linesIterator();
      while (lines.hasNext()) {

   * provided that the function is capable of accepting null input. The transformed multimap might
   * contain null values, if the function sometimes gives a null result.
   *
   * <p>The returned multimap is not thread-safe or serializable, even if the underlying multimap
   * is. The {@code equals} and {@code hashCode} methods of the returned multimap are meaningless,