* instances for each {@link Runnable} and {@link Callable} submitted to it. These tasks are run
 * with the abstract {@link #execute execute(Runnable)} method.
 *
 * <p>In addition to {@link #execute}, subclasses must implement all methods related to shutdown and
 * termination.
 *
 * @author Chris Povirk
 * @since 14.0
 */
@CheckReturnValue
@GwtIncompatible

   * AnnotatedElement}, which {@code TypeVariable} began to extend only in Java 8. Those methods
   * refer only to types present under Android, so we could implement them in {@code
   * TypeVariableImpl} today. (We could probably then make {@code TypeVariableImpl} implement {@code
   * AnnotatedElement} so that we get partial compile-time checking.)
   *
   * <p>This workaround should be removed at a distant future time when <a

 * instance for non-daemon threads.
 *
 * The task runner is also responsible for releasing held threads when the library is unloaded.
 * This is for the benefit of container environments that implement code unloading.
 *
 * Most applications should share a process-wide [TaskRunner] and use queues for per-client work.
 */
class TaskRunner(
  val backend: Backend,
  internal val logger: Logger = TaskRunner.logger,

 * (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:
 *
 * {@snippet :
 * // won't work
 * TreeTraverser<NodeType> traverser = node -> node.getChildNodes();
 * }
 *
 * Instead, you can pass a lambda expression to the {@code using} factory method:
 *

    // Changes after are not
    list.set(0, 5);

    assertEquals(ImmutableList.of(3, 4), first);
  }

  @J2ktIncompatible // Arrays.asList(...).subList() doesn't implement RandomAccess in J2KT.
  @GwtIncompatible // Arrays.asList(...).subList doesn't implement RandomAccess in GWT
  public void testPartitionRandomAccessInput() {
    Iterable<Integer> source = asList(1, 2, 3);

    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];

    // Changes after are not
    list.set(0, 5);

    assertEquals(ImmutableList.of(3, 4), first);
  }

  @J2ktIncompatible // Arrays.asList(...).subList() doesn't implement RandomAccess in J2KT.
  @GwtIncompatible // Arrays.asList(...).subList doesn't implement RandomAccess in GWT
  public void testPartitionRandomAccessInput() {
    Iterable<Integer> source = asList(1, 2, 3);

    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) {

    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];