Current LINKED_PLAN.target are UIDs - these should be changed to direct references, to allow the easier implementation of the TP engine.
I am not sure if I like this. What is a direct reference versus a UID reference?
A direct reference is just a normal reference, e.g. LINKED_PLAN.target: TASK_PLAN, whereas a UID reference is something like LINKED_PLAN.target: UID, or some other kind of id, rather than a direct object reference.
This CR is because we don’t need UID refs, it’s easier to just instantiate direct references.