code: func (r *ResourceDefinition) UserTypes() map[string]*UserTypeDefinition {
  	types := make(map[string]*UserTypeDefinition)
  	for _, a := range r.Actions {
  		for n, ut := range a.UserTypes() {
  			types[n] = ut
  		}
  	}
  	if len(types) == 0 {
  		return nil
  	}
  	return types
  }
docs: // UserTypes returns all the user types used by the resource action payloads and parameters.