<PackageReference Include="System.Reactive" Version="6.1.0" />

IEventPattern<TSender, TEventArgs>

public interface IEventPattern<TSender, TEventArgs>
Represents a .NET event invocation consisting of the strongly typed object that raised the event and the data that was generated by the event.
using System.Runtime.CompilerServices; namespace System.Reactive { [System.Runtime.CompilerServices.NullableContext(2)] public interface IEventPattern<out TSender, out TEventArgs> { TSender Sender { get; } [System.Runtime.CompilerServices.Nullable(1)] TEventArgs EventArgs { [System.Runtime.CompilerServices.NullableContext(1)] get; } } }