Flaky test: TestZkBarrierForVersionUpgrade.testZkBarrierForVersionUpgrade

./gradlew clean build

testZkBarrierForVersionUpgrade FAILED
    junit.framework.AssertionFailedError: expected:<2> but was:<1>
        at junit.framework.Assert.fail(Assert.java:57)
        at junit.framework.Assert.failNotEquals(Assert.java:329)
        at junit.framework.Assert.assertEquals(Assert.java:78)
        at junit.framework.Assert.assertEquals(Assert.java:234)
        at junit.framework.Assert.assertEquals(Assert.java:241)
        at org.apache.samza.zk.TestZkBarrierForVersionUpgrade.testZkBarrierForVersionUpgrade(TestZkBarrierForVersionUpgrade.java:140)