int i = 0;
    for (Object e : elements) {
      array[i++] = (String) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */
  protected abstract List<String> create(String[] elements);

  @Override
  public String[] createArray(int length) {
    return new String[length];
  }

   *
   * <p>Although all tasks are immediately executed in the thread that submitted the task, this
   * {@code ExecutorService} imposes a small locking overhead on each task submission in order to
   * implement shutdown and termination behavior.
   *
   * <p>Because of the nature of single-thread execution, the methods {@code scheduleAtFixedRate}
   * and {@code scheduleWithFixedDelay} are not supported by this class and will throw an

L1:[Level] and [LevelVar] now implement the [encoding.TextAppender] interface.
...

[ChaCha8] and [PCG] now implement the [encoding.BinaryAppender] interface....

    int i = 0;
    for (Object e : elements) {
      array[i++] = (String) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */
  protected abstract List<String> create(String[] elements);

  @Override
  public String[] createArray(int length) {
    return new String[length];
  }

    int i = 0;
    for (Object e : elements) {
      array[i++] = (Character) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */
  protected abstract List<Character> create(Character[] elements);

  @Override
  public Character[] createArray(int length) {

    int i = 0;
    for (Object e : elements) {
      array[i++] = (UnhashableObject) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */
  protected abstract T create(UnhashableObject[] elements);

  @Override
  public UnhashableObject[] createArray(int length) {

[Addr], [AddrPort] and [Prefix] now implement the [encoding.BinaryAppender] and

The values returned by [sha256.New] and [sha256.New224] now also implement the [encoding.BinaryAppender] interface...

 * (hdegabcf).
 *
 * <p>Null nodes are strictly forbidden.
 *
 * <p>Because this is an abstract class, not an interface, you can't use a lambda expression to
 * implement it:
 *
 * <pre>{@code
 * // won't work
 * TreeTraverser<NodeType> traverser = node -> node.getChildNodes();
 * }</pre>
 *
 * Instead, you can pass a lambda expression to the {@code using} factory method:
 *