private interface HierarchyFixtureInterface {
    // Exists only for hierarchy mapping; no members.
  }

  private interface HierarchyFixtureSubinterface extends HierarchyFixtureInterface {
    // Exists only for hierarchy mapping; no members.
  }

  private static class HierarchyFixtureParent implements HierarchyFixtureSubinterface {
    // Exists only for hierarchy mapping; no members.
  }

  private interface HierarchyFixtureInterface {
    // Exists only for hierarchy mapping; no members.
  }

  private interface HierarchyFixtureSubinterface extends HierarchyFixtureInterface {
    // Exists only for hierarchy mapping; no members.
  }

  private static class HierarchyFixtureParent implements HierarchyFixtureSubinterface {
    // Exists only for hierarchy mapping; no members.
  }