Found a few of these in the workdir log file from a JCK15 run.

[25Feb2004 19:27PST] Unexpected {2} caught from test java.lang.NullPointerException: 0
java.lang.NullPointerException
        at com.sun.javatest.TestResult.computeChecksum(TestResult.java:1933)
        at com.sun.javatest.TestResult.computeChecksum(TestResult.java:1916)
        at com.sun.javatest.TestResult.writeResults(TestResult.java:1536)
        at com.sun.javatest.TestResult.writeResults(TestResult.java:1480)
        at com.sun.javatest.DefaultTestRunner.createErrorResult(DefaultTestRunner.java:199)
        at com.sun.javatest.DefaultTestRunner.runTest(DefaultTestRunner.java:162)
        at com.sun.javatest.DefaultTestRunner.access$100(DefaultTestRunner.java:18)
        at com.sun.javatest.DefaultTestRunner$1.run(DefaultTestRunner.java:41)