Exception while removing reference: java.lang.InterruptedException
java.lang.InterruptedException
at java.lang.Object.wait(Native Method)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
at sun.java2d.Disposer.run(Disposer.java:127)
at java.lang.Thread.run(Thread.java:662)

meant “you did java.System.exit in another thread”