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

System.ServiceModel.DuplexClientBase<TChannel>

public abstract class DuplexClientBase<TChannel> : ClientBase<TChannel>
namespace System.ServiceModel { public abstract class DuplexClientBase<TChannel> : ClientBase<TChannel> where TChannel : class { public IDuplexContextChannel InnerDuplexChannel { get; } protected DuplexClientBase(InstanceContext callbackInstance); protected DuplexClientBase(InstanceContext callbackInstance, Binding binding, EndpointAddress remoteAddress); } }