Javadoc
removes the given transition from the leaving transitions.
Also the transition's source will be nulled.
This method will do nothing if the transition is null or if
the given transition is not in the list of this node's leaving
transitions.
In case this is the transition that was in the
outgoingTransitionsMap and another transition exists with the same
name, that transition (the first) will be put in the
outgoingTransitionsMap as a replacement for the removed transition.
If the transition is actually removed from the list of
leaving transitions, the transition's source will be nulled.