<PackageReference Include="System.Reactive" Version="6.0.0-preview.13" />

EventPattern<TEventArgs>

public class EventPattern<TEventArgs> : EventPattern<object, TEventArgs>
Represents a .NET event invocation consisting of the weakly typed object that raised the event and the data that was generated by the event.
public EventPattern(object sender, TEventArgs e)

Creates a new data representation instance of a .NET event invocation with the given sender and event data.