code: func ValidateRefSet(c *validation.Context, refs []string) {
  	for _, ref := range refs {
  		if strings.HasPrefix(ref, "regexp:") {
  			validateRegexpRef(c, ref)
  			continue
  		}
  
  		if !strings.HasPrefix(ref, "refs/") {
  			c.Errorf("ref must start with 'refs/' not %q", ref)
  		}
  
  		if strings.Count(ref, "/") < 2 {
  			c.Errorf(`fewer than 2 slashes in ref %q`, ref)
  		}
  	}
  }
docs: // ValidateRefSet validates strings representing a set of refs.
  //
  // It ensures that passed strings match the requirements as described in the
  // documentation for the NewRefSet function. It is designed to work with config
  // validation logic, hence one needs to pass in the validation.Context as well.