}
  }

  /** Marker interface for {@link InternalEntry} implementations for strong values. */
  interface StrongValueEntry<K, V, E extends InternalEntry<K, V, E>>
      extends InternalEntry<K, V, E> {}

  /** Marker interface for {@link InternalEntry} implementations for weak values. */
  interface WeakValueEntry<K, V, E extends InternalEntry<K, V, E>> extends InternalEntry<K, V, E> {

    }
  }

  /** Marker interface for {@link InternalEntry} implementations for strong values. */
  interface StrongValueEntry<K, V, E extends InternalEntry<K, V, E>>
      extends InternalEntry<K, V, E> {}

  /** Marker interface for {@link InternalEntry} implementations for weak values. */
  interface WeakValueEntry<K, V, E extends InternalEntry<K, V, E>> extends InternalEntry<K, V, E> {