code: func (oc *OutputChange) Encode() (*OutputChangeSrc, error) {
  	cs, err := oc.Change.Encode(cty.DynamicPseudoType)
  	if err != nil {
  		return nil, err
  	}
  	return &OutputChangeSrc{
  		Addr:      oc.Addr,
  		ChangeSrc: *cs,
  		Sensitive: oc.Sensitive,
  	}, err
  }
docs: // Encode produces a variant of the reciever that has its change values
  // serialized so it can be written to a plan file.