Running my regular tests on the current, not yet integrated state of jdk9-client, I'm getting plenty of failures like this one:

Exception in thread "main" java.lang.ExceptionInInitializerError
  at AutoBufferedFIOSTest.doTest(AutoBufferedFIOSTest.java:96)
  at javasoft.clientsqe.tonga.AbstractTongaAutoTest.invokeTest(AbstractTongaAutoTest.java:65)
  at javasoft.clientsqe.tonga.TTBuilder.main(TTBuilder.java:116)
 Caused by: java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljavax.imageio.spi.DigraphNode;
  at javax.imageio.spi.DigraphNode.dispose(DigraphNode.java:136)
  at javax.imageio.spi.PartiallyOrderedSet.remove(PartiallyOrderedSet.java:113)
  at javax.imageio.spi.SubRegistry.deregisterServiceProvider(ServiceRegistry.java:737)
  at javax.imageio.spi.SubRegistry.registerServiceProvider(ServiceRegistry.java:715)
  at javax.imageio.spi.ServiceRegistry.registerServiceProvider(ServiceRegistry.java:298)
  at javax.imageio.spi.IIORegistry.registerApplicationClasspathSpis(IIORegistry.java:212)
  at javax.imageio.spi.IIORegistry.<init>(IIORegistry.java:138)
  at javax.imageio.spi.IIORegistry.getDefaultInstance(IIORegistry.java:159)
  at javax.imageio.ImageIO.<clinit>(ImageIO.java:66)