SYSML2 — Textual notation BNF for TriggerExpression is wrong

Time and change triggers for an accept action are supposed to be parsed as a TriggerInvocationExpression with a single argument: for a time trigger, the argument is a duration or time instant, while for a change trigger it is a boolean expression. However, the textual notation BNF for TriggerExpression in 8.2.2.16.4 is not properly parsing the textual notation as an invocation with arguments. As a result, the intended argument expression for the TriggerInocationExpression will not actually be recognized as an argument of the invocation.