code: func validatePSPAllowedHostPaths(fldPath *field.Path, allowedHostPaths []policy.AllowedHostPath) field.ErrorList {
  	allErrs := field.ErrorList{}
  
  	for i, target := range allowedHostPaths {
  		if target.PathPrefix == "" {
  			allErrs = append(allErrs, field.Required(fldPath.Index(i), "is required"))
  			break
  		}
  		parts := strings.Split(filepath.ToSlash(target.PathPrefix), "/")
  		for _, item := range parts {
  			if item == ".." {
  				allErrs = append(allErrs, field.Invalid(fldPath.Index(i), target.PathPrefix, "must not contain '..'"))
  				break // even for `../../..`, one error is sufficient to make the point
  			}
  		}
  	}
  
  	return allErrs
  }
docs: // validatePSPAllowedHostPaths makes sure all allowed host paths follow:
  // 1. path prefix is required
  // 2. path prefix does not have any element which is ".."