<PackageReference Include="System.ServiceModel.Http" Version="6.0.0-rc.23205.4" />

System.ServiceModel.Channels.HttpTransportSecurityHelpers

static class HttpTransportSecurityHelpers
public static void AddIdentityMapping(EndpointAddress target, Message message)

public static void AddServerCertIdentityValidation(HttpClientHandler httpClientHandler, EndpointAddress to)

public static string GetIdentityHostHeader(EndpointAddress target)

public static void SetServerCertificateValidationCallback(HttpClientHandler handler, Func<HttpRequestMessage, X509Certificate2, X509Chain, SslPolicyErrors, bool> validator)