org.drools.simulation.impl.BatchFluentTest.testBatchSimple fails on JDK8 due to: expected:<[y]> but was:<[x]>

Description of problem:
org.drools.simulation.impl.BatchFluentTest.testBatchSimple fails on JDK8 (both Oracle and Openjdk) due to: expected:<[y]> but was:<[x]>

Error Message
expected:<[y]> but was:<[x]>
Stacktrace
org.junit.ComparisonFailure: expected:<[y]> but was:<[x]>
at org.junit.Assert.assertEquals(Assert.java:115)
at org.junit.Assert.assertEquals(Assert.java:144)
at org.drools.simulation.impl.BatchFluentTest.testBatchSimple(BatchFluentTest.java:59)

Version-Release number of selected component (if applicable):
BPM Suite 6.1.0.ER4

Steps to Reproduce:
https://jenkins.mw.lab.eng.bos.redhat.com/hudson/view/BxMS/view/BxMS-6.1/view/jBPM/view/all/job/bpms-6.1-jbpm-community-single/
use jdk1.8 in job configuration,
module drools-simulator,
test org.drools.simulation.impl.BatchFluentTest#testBatchSimple

Actual results:
org.drools.simulation.impl.BatchFluentTest.testBatchSimple fails on JDK8 due to: expected:<[y]> but was:<[x]>

Expected results:
All tests pass on all versions of JDK.

Additional info:
The same tests passes on JDK 6 and 7, both by Oracle or OpenJDK.