Race condition in ThenComposeExceptionTest.java

There is a race condition in the test java/util/concurrent/CompletableFuture/ThenComposeExceptionTest.java, where the setting of the value in an AtomicReference may occur after the assertion checking that value.

This is more likely to manifest with the VM options:

        -d64 -Xcomp -server -d64 -XX:MaxRAMFraction=8 -XX:+CreateMinidumpOnCrash -ea -esa -XX:+TieredCompilation -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -XX:+IgnoreUnrecognizedVMOptions -XX:+AggressiveOpts -XX:+IgnoreUnrecognizedVMOptions -XX:-UseCompressedOops


----------System.out:(47/3633)----------
[TestNG] Running:
  java/util/concurrent/CompletableFuture/ThenComposeExceptionTest.java

test ThenComposeExceptionTest.testThenCompose("thenCompose and completeExceptionally", ThenComposeExceptionTest$$Lambda$4/727334714@75669bce, ThenComposeExceptionTest$$Lambda$1/1619870038@1ee12b96, ThenComposeExceptionTest$$Lambda$3/127442007@c009aaa): success
test ThenComposeExceptionTest.testThenCompose("thenComposeAsync and completeExceptionally", ThenComposeExceptionTest$$Lambda$4/727334714@75669bce, ThenComposeExceptionTest$$Lambda$2/247747923@7aff76da, ThenComposeExceptionTest$$Lambda$3/127442007@c009aaa): failure
java.lang.AssertionError: Incorrect exception reported on whenComplete expected [true] but found [false]
at org.testng.Assert.fail(Assert.java:94)
at org.testng.Assert.failNotEquals(Assert.java:494)
at org.testng.Assert.assertTrue(Assert.java:42)
at ThenComposeExceptionTest.testThenCompose(ThenComposeExceptionTest.java:107)