Descendent type [IssuedSecurityToken] of type [SecurityToken] is not discriminated

Consider the following code:

class abstract SecurityToken : Entity<long> { /* ... */ }

class abstract IssuedSecurityToken : SecurityToken { /* ... */ }

[Discriminator(Attribute = "Discriminator", Value = 1)]

class AccessSecurityToken : IssuedSecurityToken { /* ... */ }

[Discriminator(Attribute = "Discriminator", Value = 2)]

class RequestSecurityToken : IssuedSecurityToken { /* ... */ }

The first time I access the database, I get the following error:

Descendent type [IssuedSecurityToken] of type [SecurityToken] is not discriminated

I can add Discriminator attribute to IssuedSecurityToken, but it seems rather superfluous since IssuedSecurityToken is abstract. Just curious why this requirement exists.

Thanks, Werner

The honest answer is that the chap who wrote the inheritance subsystem back in 2007 didn't make an exclusion for abstract classes, and the issue has never previously come up! I'm pretty sure we could safely skip the discriminator check for abstract classes, and I'll log a bug for it -- thanks for drawing it to our attention!