On my Oracle Linux 7.7 VM I consistently get the following test failure:

$ gradle --continue --info -PFULL_TEST=true cleanTest :systemTests:test --tests test.com.sun.javafx.image.impl.ImageRaceTest

test.com.sun.javafx.image.impl.ImageRaceTest > testImageInitializationRaceCondition FAILED
    java.lang.RuntimeException: Initializer Thread[ByteGrayAlpha.ToByteGrayAlphaPre Initializer,5,main] never started
        at test.com.sun.javafx.image.impl.ImageRaceTest.forkAndJoinInitializers(ImageRaceTest.java:82)
        at test.com.sun.javafx.image.impl.ImageRaceTest.testImageInitializationRaceCondition(ImageRaceTest.java:240)

This is due to the following fragile code in the test:

    while (!ready) { yield(); }

Thread.yield is documented to be a hint and should not be used in this manner. The fix is to change Thread.yield to Thread.sleep(1) in the two places in the test it occurs.