<PackageReference Include="System.ServiceModel.Primitives" Version="8.1.2" />

System.ServiceModel.Security.X509CertificateValidationMode

namespace System.ServiceModel.Security { public enum X509CertificateValidationMode { ChainTrust = 2, Custom = 4, None = 0, PeerOrChainTrust = 3, PeerTrust = 1 } }