code: func ctyNullBlockSetAsEmpty(in cty.Value) cty.Value {
  	if !in.IsNull() {
  		return in
  	}
  	// Dynamically-typed attributes are not supported inside blocks backed by
  	// sets, so our result here is always a set.
  	return cty.SetValEmpty(in.Type().ElementType())
  }
docs: // ctyNullBlockSetAsEmpty either returns the given value verbatim if it is non-nil
  // or returns an empty value of a suitable type to serve as a placeholder for it.