private static ClassOwnership detectJvmBehavior() {
      class LocalClass<T> {}
      Class<?> subclass = new LocalClass<String>() {}.getClass();
      // requireNonNull is safe because we're examining a type that's known to have a superclass.
      ParameterizedType parameterizedType =
          requireNonNull((ParameterizedType) subclass.getGenericSuperclass());
      for (ClassOwnership behavior : ClassOwnership.values()) {

   * elements and to build again.
   *
   * @since 2.0
   */
  public static class Builder<E> extends ImmutableCollection.Builder<E> {
    /*
     * `impl` is null only for instances of the subclass, ImmutableSortedSet.Builder. That subclass
     * overrides all the methods that access it here. Thus, all the methods here can safely assume
     * that this field is non-null.
     */
    private @Nullable SetBuilderImpl<E> impl;

  }

  /**
   * Returns a cache loader based on an <i>existing</i> supplier instance. Note that there's no need
   * to create a <i>new</i> supplier just to pass it in here; just subclass {@code CacheLoader} and
   * implement {@link #load load} instead.
   *
   * <p>The returned object is serializable if {@code supplier} is serializable.
   *

    assertThat(future.isDone()).isFalse();
    assertThat(future.set(1)).isTrue();
    assertSuccessful(future, 1);
  }

  /** Concrete subclass for testing. */
  private static class TestedFuture<V> extends AbstractFuture<V> {
    private static <V> TestedFuture<V> create() {
      return new TestedFuture<V>();
    }
  }

      if (result) {
        executionList.execute();
      }
      return result;
    }

    /**
     * Following the contract of {@link AbstractQueuedSynchronizer} we create a private subclass to
     * hold the synchronizer. This synchronizer is used to implement the blocking and waiting calls
     * as well as to handle state changes in a thread-safe manner. The current state of the future

      }
      return processor.getResult();
    }

    @Override
    public String toString() {
      return "CharSource.wrap(" + Ascii.truncate(seq, 30, "...") + ")";
    }
  }

  /**
   * Subclass specialized for string instances.
   *
   * <p>Since Strings are immutable and built into the jdk we can optimize some operations
   *
   * <ul>

      }
      return processor.getResult();
    }

    @Override
    public String toString() {
      return "CharSource.wrap(" + Ascii.truncate(seq, 30, "...") + ")";
    }
  }

  /**
   * Subclass specialized for string instances.
   *
   * <p>Since Strings are immutable and built into the jdk we can optimize some operations
   *
   * <ul>

   * of SerializedForm whose readResolve() method returns objects of the subclass type.
   */
  @J2ktIncompatible // serialization
  Object writeReplace() {
    return new SerializedForm<>(this);
  }

  @J2ktIncompatible // java.io.ObjectInputStream
  private void readObject(ObjectInputStream stream) throws InvalidObjectException {

    }
  }

  /*
   * TODO(cpovirk): surely we can find a less ugly solution than a class that accepts 3 parameters,
   * exposes as many getters, does work in the constructor, and has both a superclass and a subclass
   */
  public static class SortedMapSubmapTestMapGenerator<
          K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingTestMapGenerator<K, V> implements TestSortedMapGenerator<K, V> {

 *
 * <p>Subclasses are guaranteed that the life cycle methods ({@link #runOneIteration}, {@link
 * #startUp} and {@link #shutDown}) will never run concurrently. Notably, if any execution of {@link
 * #runOneIteration} takes longer than its schedule defines, then subsequent executions may start
 * late. Also, all life cycle methods are executed with a lock held, so subclasses can safely modify