code: func (wit WorkItemType) ConvertWorkItemStorageToModel(workItem WorkItemStorage) (*WorkItem, error) {
  	result := WorkItem{
  		ID:                     workItem.ID,
  		Number:                 workItem.Number,
  		Type:                   workItem.Type,
  		Version:                workItem.Version,
  		Fields:                 map[string]interface{}{},
  		SpaceID:                workItem.SpaceID,
  		relationShipsChangedAt: workItem.RelationShipsChangedAt,
  	}
  
  	for name, field := range wit.Fields {
  		var err error
  		if name == SystemCreatedAt {
  			continue
  		}
  		result.Fields[name], err = field.ConvertFromModel(name, workItem.Fields[name])
  		if err != nil {
  			return nil, errs.WithStack(err)
  		}
  		result.Fields[SystemOrder] = workItem.ExecutionOrder
  	}
  
  	return &result, nil
  }
docs: // ConvertWorkItemStorageToModel converts a workItem from the storage/persistence layer into a workItem of the model domain layer