FULL PRODUCT VERSION :
Java version: 1.7.0_79, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u79-2.5.5-1

ADDITIONAL OS VERSION INFORMATION :
Linux Debian GNU/Linux unstable (sid)

A DESCRIPTION OF THE PROBLEM :
This is an upstream bug report for:
https://josm.openstreetmap.de/ticket/11530

An ArrayIndexOutOfBoundsException is thrown when sun.awt.X11.XToolkit tries to log a message.

The stacktrace mentions an index of 85. The portion of code where the bug occurs is:

83 String More ...getFieldsAsString() {
84 StringBuilder ret = new StringBuilder(1320);
85
86 ret.append("type = ").append( XlibWrapper.eventToString[get_type()] ).append(", ");

So get_type() returns 85, but XlibWrapper.eventToString[ contains only 36 items:

51 public final static String eventToString[]=
52 {"<none:0>", "<none:1>", "KeyPress", "KeyRelease", "ButtonPress", "ButtonRelease",
53 "MotionNotify", "EnterNotify", "LeaveNotify", "FocusIn", "FocusOut",
54 "KeymapNotify", "Expose", "GraphicsExpose", "NoExpose", "VisibilityNotify",
55 "CreateNotify", "DestroyNotify", "UnmapNotify", "MapNotify", "MapRequest",
56 "ReparentNotify", "ConfigureNotify", "ConfigureRequest", "GravityNotify",
57 "ResizeRequest", "CirculateNotify", "CirculateRequest", "PropertyNotify",
58 "SelectionClear", "SelectionRequest", "SelectionNotify", "ColormapNotify",
59 "ClientMessage", "MappingNotify", "LASTEvent"};



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
no error
ACTUAL -
ArrayIndexOutOfBoundsException

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.ArrayIndexOutOfBoundsException: 85
at sun.awt.X11.XEvent.getFieldsAsString(XEvent.java:86)
at sun.awt.X11.XWrapperBase.toString(XWrapperBase.java:37)
at sun.awt.X11.XEvent.toString(XEvent.java:8)
at java.lang.String.valueOf(String.java:2847)
at sun.util.logging.PlatformLogger$JavaLoggerProxy.doLog(PlatformLogger.java:663)
at sun.util.logging.PlatformLogger.finer(PlatformLogger.java:424)
at sun.awt.X11.XToolkit.run(XToolkit.java:559)
at sun.awt.X11.XToolkit.run(XToolkit.java:505)
at java.lang.Thread.run(Thread.java:745)

REPRODUCIBILITY :
This bug can be reproduced often.