UnsupportedOperationException: Accumulate function (min) does not have reverseSupport - drools

Question

I am using drools with optaplanner but when i start project sometimes it returns this exception and sometimes didn't return any exception with same code.
THE RULE:
rule "groupedSteps"
when
$Act : Action(this !=null,Step != null,$step : getStepType().getId(),isCanItBeGrouped(),period !=null)
accumulate(
Action(this != null,Step != null,period != null,isCanItBeGrouped(),getStepType().getId() == $step,$startTime : getStartTime(),getStartTime() >= 0);
$firstStart : min(checkStartTimeIsBigOrEqualToZero($startTime))
)
Action($firstStart == getStartTime(),$step == getStepType().getId(),isCanItBeGrouped() == true,$xMachine : Machine, $employee : Employee,period != null)
Action(this != null,isCanItBeGrouped() == true,getStepType().getId() == $step,$xStartTime : getStartTime(),$xMach : Machine,$xEmployee : Employee,period != null,Employee !=null)
eval($xStartTime < (int)$firstStart || $xEmployee != $employee || $xMachine != $xMach)
then
scoreHolder.addHardConstraintMatch(kcontext, -5);
end
THE checkStartTimeIsBigOrEqualToZero METHOD:
function int checkStartTimeIsBigOrEqualToZero(int startTime)
{
try{
if (startTime >= 0)
return startTime;
else
return 99999;
}
catch (Exception ex)
{
return 99999;
}
}
FULL ERROR:
Exception in thread "AWT-EventQueue-0" Exception executing consequence
for rule "groupedSteps" in org.optaplanner.examples.opnext.solver:
java.lang.UnsupportedOperationException: Accumulate function (min)
used in rule(s) [groupedSteps] does not have reverseSupport at
org.drools.core.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
at
org.drools.core.common.DefaultAgenda.handleException(DefaultAgenda.java:1247)
at
org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:438)
at
org.drools.core.phreak.RuleExecutor.fireActivation(RuleExecutor.java:379)
at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:135)
at
org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:88)
at
org.drools.core.concurrent.AbstractRuleEvaluator.internalEvaluateAndFire(AbstractRuleEvaluator.java:34)
at
org.drools.core.concurrent.SequentialRuleEvaluator.evaluateAndFire(SequentialRuleEvaluator.java:43)
at
org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:1067)
at
org.drools.core.common.DefaultAgenda.internalFireAllRules(DefaultAgenda.java:1014)
at
org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1006)
at
org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1318)
at
org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1309)
at
org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1293)
at
org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.calculateScore(DroolsScoreDirector.java:117)
at
org.optaplanner.examples.common.business.SolutionBusiness.getScore(SolutionBusiness.java:218)
at
org.optaplanner.examples.opnext.business.CalculatorClass.bestSolutionChanged(CalculatorClass.java:149)
at
org.optaplanner.examples.common.business.SolutionBusiness.lambda$null$0(SolutionBusiness.java:247)
at
java.awt.event.InvocationEvent.dispatch$$$capture(InvocationEvent.java:311)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java) at
java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756) at
java.awt.EventQueue.access$500(EventQueue.java:97) at
java.awt.EventQueue$3.run(EventQueue.java:709) at
java.awt.EventQueue$3.run(EventQueue.java:703) at
java.security.AccessController.doPrivileged(Native Method) at
java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726) at
java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at
java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: java.lang.UnsupportedOperationException: Accumulate
function (min) used in rule(s) [groupedSteps] does not have
reverseSupport at
org.drools.core.reteoo.FromNodeLeftTuple.getAccumulatedObjects(FromNodeLeftTuple.java:105)
at
org.drools.core.common.AgendaItem.getObjectsDeep(AgendaItem.java:79)
at
org.drools.core.reteoo.RuleTerminalNodeLeftTuple.getObjectsDeep(RuleTerminalNodeLeftTuple.java:359)
at
org.optaplanner.core.api.score.holder.AbstractScoreHolder.extractJustificationList(AbstractScoreHolder.java:118)
at
org.optaplanner.core.api.score.holder.AbstractScoreHolder.registerConstraintMatch(AbstractScoreHolder.java:88)
at
org.optaplanner.core.api.score.buildin.hardmediumsoft.HardMediumSoftScoreHolder.addHardConstraintMatch(HardMediumSoftScoreHolder.java:58)
at
org.optaplanner.examples.opnext.solver.Rule_groupedSteps547703499.defaultConsequence(Rule_groupedSteps547703499.java:21)
at
org.optaplanner.examples.opnext.solver.Rule_groupedSteps547703499DefaultConsequenceInvokerGenerated.evaluate(Unknown
Source) at
org.optaplanner.examples.opnext.solver.Rule_groupedSteps547703499DefaultConsequenceInvoker.evaluate(Unknown
Source) at
org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:431)
... 30 more