elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements (with "
            + "a null element counting as having a hash of zero).",
        expectedHashCode,
        getSet().hashCode());
  }

  /**
   * Returns the {@link Method} instances for the test methods in this class which call {@code

    elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements (with "
            + "a null element counting as having a hash of zero).",
        expectedHashCode,
        getSet().hashCode());
  }

  /**
   * Returns the {@link Method} instances for the test methods in this class which call {@code

            }
            return id;
        }
    }

    /**
     * Statistics data object that stores timestamped events and maintains reference counting.
     * Extends LinkedHashMap to store event names mapped to their timestamps.
     * Includes reference counting for multi-threaded access tracking.
     */
    public static class StatsObject extends LinkedHashMap<String, Long> {

    ArrayList<ListenableFuture<Integer>> lengthChecks = new ArrayList<>();
    List<Integer> completeLengthChecks;
    int baseStackDepth;
    ExecutorService service = newFixedThreadPool(5);
    try {
      // Avoid counting frames from the executor itself, or the ExecutionSequencer
      baseStackDepth =
          serializer
              .submit(
                  new Callable<Integer>() {
                    @Override

   * @throws IllegalArgumentException if {@code node} is not an element of this network
   */
  Set<E> outEdges(N node);

  /**
   * Returns the count of {@code node}'s {@link #incidentEdges(Object) incident edges}, counting
   * self-loops twice (equivalently, the number of times an edge touches {@code node}).
   *
   * <p>For directed networks, this is equal to {@code inDegree(node) + outDegree(node)}.
   *