TwoInputStreamTaskTest.testWatermarkAndWatermarkStatusForwarding failed

Error: 07:48:06 07:48:06.643 [ERROR] Tests run: 11, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.309 s <<< FAILURE! -- in org.apache.flink.streaming.runtime.tasks.TwoInputStreamTaskTest
Error: 07:48:06 07:48:06.646 [ERROR] org.apache.flink.streaming.runtime.tasks.TwoInputStreamTaskTest.testWatermarkAndWatermarkStatusForwarding -- Time elapsed: 0.036 s <<< FAILURE!
Feb 16 07:48:06 Output was not correct.: array lengths differed, expected.length=8 actual.length=7; arrays first differed at element [6]; expected:<Watermark @ 5> but was:<Watermark @ 6>
Feb 16 07:48:06 	at org.junit.internal.ComparisonCriteria.arrayEquals(ComparisonCriteria.java:78)
Feb 16 07:48:06 	at org.junit.internal.ComparisonCriteria.arrayEquals(ComparisonCriteria.java:28)
Feb 16 07:48:06 	at org.junit.Assert.internalArrayEquals(Assert.java:534)
Feb 16 07:48:06 	at org.junit.Assert.assertArrayEquals(Assert.java:285)
Feb 16 07:48:06 	at org.apache.flink.streaming.util.TestHarnessUtil.assertOutputEquals(TestHarnessUtil.java:59)
Feb 16 07:48:06 	at org.apache.flink.streaming.runtime.tasks.TwoInputStreamTaskTest.testWatermarkAndWatermarkStatusForwarding(TwoInputStreamTaskTest.java:248)
Feb 16 07:48:06 	at java.lang.reflect.Method.invoke(Method.java:498)
Feb 16 07:48:06 Caused by: java.lang.AssertionError: expected:<Watermark @ 5> but was:<Watermark @ 6>
Feb 16 07:48:06 	at org.junit.Assert.fail(Assert.java:89)
Feb 16 07:48:06 	at org.junit.Assert.failNotEquals(Assert.java:835)
Feb 16 07:48:06 	at org.junit.Assert.assertEquals(Assert.java:120)
Feb 16 07:48:06 	at org.junit.Assert.assertEquals(Assert.java:146)
Feb 16 07:48:06 	at org.junit.internal.ExactComparisonCriteria.assertElementsEqual(ExactComparisonCriteria.java:8)
Feb 16 07:48:06 	at org.junit.internal.ComparisonCriteria.arrayEquals(ComparisonCriteria.java:76)
Feb 16 07:48:06 	... 6 more