* </p>
     *
     * @param disposable
     *            A disposable resource. Must not be {@literal null}.
     */
    public static synchronized void addFirst(final Disposable disposable) {
        assertArgumentNotNull("disposable", disposable);
        disposables.addFirst(disposable);
    }

    /**
     * Unregisters a disposable resource.
     *
     * @param disposable

    abstract @Nullable N visitNext(Deque<Iterator<? extends N>> horizon);
  }

  /** Poor man's method reference for {@code Deque::addFirst} and {@code Deque::addLast}. */
  private enum InsertionOrder {
    FRONT {
      @Override
      <T> void insertInto(Deque<T> deque, T value) {
        deque.addFirst(value);
      }
    },
    BACK {
      @Override
      <T> void insertInto(Deque<T> deque, T value) {

        }

        val nextPlan = connectResult.nextPlan
        if (nextPlan != null) {
          // Try this plan's successor before deferred plans because it won the race!
          routePlanner.deferredPlans.addFirst(nextPlan)
        }
      }
    } finally {
      cancelInFlightConnects()
    }

    throw firstException!!
  }

  /**

  @CanIgnoreReturnValue
  @ParametricNullness
  public <C extends @Nullable Closeable> C register(@ParametricNullness C closeable) {
    if (closeable != null) {
      stack.addFirst(closeable);
    }

    return closeable;
  }

  /**
   * Stores the given throwable and rethrows it. It will be rethrown as is if it is an {@code

        }
    }

    /**
     * Initializes the {@link Logger}.
     */
    protected static synchronized void initialize() {
        DisposableUtil.addFirst(() -> {
            initialized = false;
            loggers.clear();
            factory.releaseAll();
        });
        initialized = true;
    }

    /**