<PackageReference Include="System.Reactive" Version="6.0.1" />

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.
TEventArgs EventArgs { get; }

Gets the event data that was generated by the event.

TSender Sender { get; }

Gets the sender object that raised the event.