throw new InvalidObjectException("Use SerializedForm");
  }

  // This class is never actually serialized directly, but we have to make the
  // warning go away (and suppressing would suppress for all nested classes too)
  private static final long serialVersionUID = 0;

  /**
   * Not supported. Use {@link #toImmutableSortedMap}, which offers better type-safety, instead.

    throw new InvalidObjectException("Use SerializedForm");
  }

  // This class is never actually serialized directly, but we have to make the
  // warning go away (and suppressing would suppress for all nested classes too)
  private static final long serialVersionUID = 0;

  /**
   * Not supported. Use {@link #toImmutableSortedMap}, which offers better type-safety, instead.