Documentation unclear about linking inherited objects

The (very nice) doctrine documentation fails to mention anything about how inherited objects handle relations.

I.e. if I got the model:
Entity:
columns:
username: string(20)
password: string(16)
created_at: timestamp
updated_at: timestamp

User:
inheritance:
extends: Entity
type: column_aggregation
keyField: type
keyValue: 1

Group:
inheritance:
extends: Entity
type: column_aggregation
keyField: type
keyValue: 2

Topic:
content: string
entity_id: integer
relations:
User:
class: Entity
local: entity_id
foreign: id

Can I then define both users and groups to link to Topic?