It has the same fields as `HeroBase`, so it won't include `secret_name`.

Finally, the identity of our heroes is protected! 🥷

It also re-declares `id: int`. By doing this, we are making a **contract** with the API clients, so that they can always expect the `id` to be there and to be an `int` (it will never be `None`).

/// tip

        service.startAsync();
      } catch (IllegalStateException e) {
        // This can happen if the service has already been started or stopped (e.g. by another
        // service or listener). Our contract says it is safe to call this method if
        // all services were NEW when it was called, and this has already been verified above, so we
        // don't propagate the exception.

        service.startAsync();
      } catch (IllegalStateException e) {
        // This can happen if the service has already been started or stopped (e.g. by another
        // service or listener). Our contract says it is safe to call this method if
        // all services were NEW when it was called, and this has already been verified above, so we
        // don't propagate the exception.

    Object[] copyTo = new Object[size];
    arraycopy(queue, 0, copyTo, 0, size);
    return copyTo;
  }

  /**
   * Returns the comparator used to order the elements in this queue. Obeys the general contract of
   * {@link PriorityQueue#comparator}, but returns {@link Ordering#natural} instead of {@code null}
   * to indicate natural ordering.
   */
  public Comparator<? super E> comparator() {
    return minHeap.ordering;

      // checking isAcquiredByCurrentThread(). For ordered locks, however, this
      // can happen because multiple locks may share the same LockGraphNode. In
      // this situation, throw an IllegalStateException as defined by contract
      // described in the documentation of WithExplicitOrdering.
      Preconditions.checkState(
          this != acquiredLock,
          "Attempted to acquire multiple locks with the same rank %s",

          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.
          // There is no contract one way or another as long as isSubtypeOf() works as expected.
          combined.addAll(asList(typeParam.getBounds()));
          if (combined.size() > 1) { // Object is implicit and only useful if it's the only bound.

to be bound by the terms and conditions of this Creative Commons
Attribution 4.0 International Public License ("Public License"). To the
extent this Public License may be interpreted as a contract, You are
granted the Licensed Rights in consideration of Your acceptance of
these terms and conditions, and the Licensor grants You such rights in
consideration of benefits the Licensor receives from making the

   * this fluent iterable supports it. Note that it is <i>not</i> possible to delete the last
   * skipped element by immediately calling {@code remove()} on the returned fluent iterable's
   * iterator, as the {@code Iterator} contract states that a call to {@code * remove()} before a
   * call to {@code next()} will throw an {@link IllegalStateException}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#skip} (same).
   */

 * graph construction.
 * <p>
 * Extend this class {@code createXXX()} methods and override to customize, if needed. The contract of this class makes
 * sure that these (potentially overridden) methods are invoked only once, and instance created by those methods are
 * memorized and kept as long as supplier instance is kept open.
 * <p>

        if (cmp < 0) {
          elements[unique++] = elements[i];
        } else if (cmp > 0) {
          throw new AssertionError(
              "Comparator " + comparator + " compare method violates its contract");
        }
      }
      Arrays.fill(elements, unique, n, null);
      n = unique;
    }

    /**
     * Adds {@code element} to the {@code ImmutableSortedSet}. If the {@code ImmutableSortedSet}