// restore tuple source from before the start of the sub network
context.setTupleSource( tupleSource );
// create a tuple start equals constraint and set it in the context
final TupleStartEqualsConstraint constraint = TupleStartEqualsConstraint.getInstance();
final List<BetaNodeFieldConstraint> predicates = new ArrayList<BetaNodeFieldConstraint>();
predicates.add( constraint );
context.setBetaconstraints( predicates );
existSubNetwort = true;