/// <summary>
/// Gets the validation errors for a specified property or for the entire entity.
/// </summary>
/// <param name="propertyName">The name of the property to retrieve validation errors for,
/// or <value>null</value> or <see cref="String.Empty"/> to retrieve entity-level errors.</param>
protected override IEnumerable <TError> GetErrors(string propertyName)
{
return(Errors.AsyncGet(GetErrorsAsync, propertyName));
}