code: func (b *PolicyBindings) UnmarshalJSON(data []byte) error {
  	bindings := []roleBinding{}
  	if err := json.Unmarshal(data, &bindings); err != nil {
  		return err
  	}
  	newOne := make(PolicyBindings, len(bindings))
  	for _, item := range bindings {
  		members := make(membersSet, len(item.Members))
  		for _, member := range item.Members {
  			members[member] = struct{}{}
  		}
  		newOne[item.Role] = members
  	}
  	*b = newOne
  	return nil
  }
docs: // UnmarshalJSON is part of json.Unmarshaler interface.