<PackageReference Include="System.Configuration.ConfigurationManager" Version="5.0.0-preview.2.20160.6" />

PositiveTimeSpanValidatorAttribute

Declaratively instructs the .NET Framework to perform time validation on a configuration property. This class cannot be inherited.
namespace System.Configuration { [AttributeUsage(AttributeTargets.Property)] public sealed class PositiveTimeSpanValidatorAttribute : ConfigurationValidatorAttribute { public override ConfigurationValidatorBase ValidatorInstance => new PositiveTimeSpanValidator(); } }