I occasionally see the following failure on my macOS 10.12 system:

test.javafx.embed.swing.SwingNodeMemoryLeakTest > testSwingNodeMemoryLeak FAILED
    java.lang.AssertionError: expected:<10> but was:<0>
        at org.junit.Assert.fail(Assert.java:91)
        at org.junit.Assert.failNotEquals(Assert.java:645)
        at org.junit.Assert.assertEquals(Assert.java:126)
        at org.junit.Assert.assertEquals(Assert.java:470)
        at org.junit.Assert.assertEquals(Assert.java:454)
        at test.javafx.embed.swing.SwingNodeMemoryLeakTest.testSwingNodeMemoryLeak(SwingNodeMemoryLeakTest.java:89)