Could someone perhaps also elaborate on the properties? There are zero comments in source, so it is difficult to know what the intended purpose is. Especially in comparison and/or contrast of ReturnedClass, which I take to mean the intended CLR type in question, DefaultValue.

DefaultValue, somewhat obvious albeit without comments, in my case looking at NodaTime.Duration.Zero, right. So if we're talking about NodaTime.Duration, then what is PrimitiveClass in that picture? Could be for instance string? Or System.TimeSpan? Or what else?

Thank you...

abstract System.Type PrimitiveClass { get; }
abstract object DefaultValue { get; }