/// <inheritdoc/>
 protected override Provider VisitFreeText(FreeTextProvider provider)
 {
     OnRecursionEntrance(provider);
     OnRecursionExit(provider);
     return(provider);
 }
 /// <summary>
 /// Visits the <see cref="FreeTextProvider"/>.
 /// </summary>
 /// <param name="provider">FreeText provider.</param>
 /// <returns></returns>
 protected abstract Provider VisitFreeText(FreeTextProvider provider);