[DocDB] Flaky test: org.yb.loadtester.TestMasterLeaderDecommission#testMasterLeaderDecommission is flaky

15:35:24.379 (main) [ERROR - org.yb.BaseYBTest$1$2.logEventDetails(BaseYBTest.java:248)] YB Java test failed: class="org.yb.loadtester.TestMasterLeaderDecommission", method="testMasterLeaderDecommission"
java.lang.NullPointerException: null
	at org.yb.loadtester.TestClusterBase.removeMaster(TestClusterBase.java:399)
	at org.yb.loadtester.TestMasterLeaderDecommission.testMasterLeaderDecommission(TestMasterLeaderDecommission.java:57)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:288)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:282)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.lang.Thread.run(Thread.java:748)