Dialog class has been updated to use new public EventQueue.createSecondaryLoop() API for modality (see JDK-6949936).
JOptionPane should be updated in the same way to get rid of internal API usage (like reflection or AWTAccessor).

SecondaryLoop Javadoc: https://docs.oracle.com/javase/7/docs/api/java/awt/SecondaryLoop.html
The SecondaryLoop API discussion: http://mail.openjdk.java.net/pipermail/awt-dev/2010-August/001343.html