Autorelease build failure, intermittent Unit-test failures in aclservice-impl.

Exceptions seen in unit test results

• NulPointerException 

Running org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test

Tests run: 12, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 17.398 sec <<< FAILURE! - in org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test

newInterfaceWithIcmpAcl(org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test)  Time elapsed: 0.464 sec  <<< ERROR!

java.lang.NullPointerException

       at org.opendaylight.genius.mdsalutil.interfaces.testutils.TestIMdsalApiManager.lambda$sortFlows$0(TestIMdsalApiManager.java:164)

• Test results comparison failures

Running org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulTest
Tests run: 12, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 18.227 sec - in org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulTest
Running org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test
Tests run: 12, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 5.337 sec <<< FAILURE! - in org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test
newInterfaceWithIcmpAcl(org.opendaylight.netvirt.aclservice.tests.AclServiceStatefulIPv6Test) Time elapsed: 1.031 sec <<< FAILURE!
org.junit.ComparisonFailure: Expected and actual beans do not match expected:<...ss_ICMPv6_123_987_13[3_Permit_"

check  here [0] for details

[0] https://lists.opendaylight.org/pipermail/netvirt-dev/2018-December/007657.html