code: func (v *ValidationDefinition) AddRequired(required []string) {
  	for _, r := range required {
  		found := false
  		for _, rr := range v.Required {
  			if r == rr {
  				found = true
  				break
  			}
  		}
  		if !found {
  			v.Required = append(v.Required, r)
  		}
  	}
  }
docs: // AddRequired merges the required fields from other into v