<PackageReference Include="System.Reactive" Version="6.0.2" />

System.Reactive.Joins.ActivePlan<T1, T2, T3, T4, T5, T6, T7, T8, T9>

sealed class ActivePlan<T1, T2, T3, T4, T5, T6, T7, T8, T9> : ActivePlan
namespace System.Reactive.Joins { }