String instEndEL = input.getEnd();
ExpressionHelper evaluator = ExpressionHelper.get();
Validity processValidity = ProcessHelper.getCluster(process, clusterName).getValidity();
ExpressionHelper.setReferenceDate(processValidity.getStart());
Date instStart = evaluator.evaluate(instStartEL, Date.class);
if (instStart.before(feedStart))
throw new ValidationException("Start instance " + instStartEL + " of feed " + feed.getName()
+ " is before the start of feed " + feedValidity.getStart() + " for cluster " + clusterName);
Date instEnd = evaluator.evaluate(instEndEL, Date.class);