FUML11 — Null tokens are not sent on by control nodes

Specification: Semantics of a Foundational Subset for Executable UML Models (fUML), v1.0 (formal/2011-02-02)
Subclause: 8.5.2.2.15 ObjectNodeActivation

When an object node has no tokens, ObjectNodeActivation::sendOffers creates a null token to send. However, the holder attribute of this token is not set. This means that, even though the token gets offered, when a node tries to take it from the offering edge instance, the token is considered to have been withdrawn and is not passed on to the token. The effect of this is, in particular, that control node activations will never pass on null tokens, which is incorrect.

To avoid this, sendOffers should set the holder of the null token to be the object node sending it.

agreed