/// <summary>Determines whether the specified object is valid.</summary>
/// <param name="validationContext">The validation context.</param>
/// <returns>A collection that holds failed-validation information.</returns>
public IEnumerable <ValidationResult> Validate(ValidationContext validationContext)
{
if (Any.Any() && All.Any() || !All.Any() && !Any.Any())
{
return(new []
{
Any.Any() && All.Any() ?
new ValidationResult($"Both {nameof(Any)} and {nameof(All)} properties have items, which is invalid. One or the other must have items provided.") :
new ValidationResult($"Neither {nameof(Any)} and {nameof(All)} properties have items, which is invalid. One or the other must have items provided."),
});
}
return(Enumerable.Empty <ValidationResult>());
}