"sort values" results in exception

[malenki]

What steps will reproduce the problem?

1. Have a data layer in JOSM with at least one object with two tags
2. select it
3. Click on "Value" in the properties window.

What is the expected result?

Sort values

What happens instead?

Exception

Please provide any additional information below. Attach a screenshot if possible.

The possibility to sort keys and values and seemingly also the issue was introduced between r8973 and r8985, sorting keys works fine.
I set the priority to "critical" since it is nearly impossible to continue mapping after having triggered this exception because every selection and de-selection of tagged objects will throw another exception.
Tested with blank ~/.josm
Exists also in r8993

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2015-11-03 02:34:09
Last Changed Author: Don-vip
Revision: 8985
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2015-11-03 01:12:42 +0100 (Tue, 03 Nov 2015)
Last Changed Rev: 8985

Identification: JOSM/1.5 (8985 de) Linux LMDE 2 Betsy
Memory Usage: 303 MB / 2222 MB (144 MB allocated, but free)
Java version: 1.7.0_85, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u85-2.6.1-6+deb8u1
VM arguments: [-Dsun.java2d.opengl=false]
Dataset consistency test: No problems found


Last errors/warnings:
- E: java.lang.ClassCastException: java.util.TreeMap cannot be cast to java.lang.String

java.lang.ClassCastException: java.util.TreeMap cannot be cast to java.lang.String
	at java.text.Collator.compare(Collator.java:327)
	at javax.swing.DefaultRowSorter.compare(DefaultRowSorter.java:968)
	at javax.swing.DefaultRowSorter.access$100(DefaultRowSorter.java:112)
	at javax.swing.DefaultRowSorter$Row.compareTo(DefaultRowSorter.java:1376)
	at javax.swing.DefaultRowSorter$Row.compareTo(DefaultRowSorter.java:1366)
	at java.util.Arrays.mergeSort(Arrays.java:573)
	at java.util.Arrays.legacyMergeSort(Arrays.java:478)
	at java.util.Arrays.sort(Arrays.java:470)
	at javax.swing.DefaultRowSorter.sort(DefaultRowSorter.java:607)
	at javax.swing.DefaultRowSorter.setSortKeys(DefaultRowSorter.java:319)
	at javax.swing.DefaultRowSorter.toggleSortOrder(DefaultRowSorter.java:480)
	at javax.swing.plaf.basic.BasicTableHeaderUI$MouseInputHandler.mouseClicked(BasicTableHeaderUI.java:112)
	at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
	at java.awt.Component.processMouseEvent(Component.java:6519)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3312)
	at java.awt.Component.processEvent(Component.java:6281)
	at java.awt.Container.processEvent(Container.java:2229)
	at java.awt.Component.dispatchEventImpl(Component.java:4872)
	at java.awt.Container.dispatchEventImpl(Container.java:2287)
	at java.awt.Component.dispatchEvent(Component.java:4698)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4501)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
	at java.awt.Container.dispatchEventImpl(Container.java:2273)
	at java.awt.Window.dispatchEventImpl(Window.java:2719)
	at java.awt.Component.dispatchEvent(Component.java:4698)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:747)
	at java.awt.EventQueue.access$300(EventQueue.java:103)
	at java.awt.EventQueue$3.run(EventQueue.java:706)
	at java.awt.EventQueue$3.run(EventQueue.java:704)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
	at java.awt.EventQueue$4.run(EventQueue.java:720)
	at java.awt.EventQueue$4.run(EventQueue.java:718)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:717)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

[Don-vip]

introduced in r8980?

[simon04]

In 8996/josm:

fix #12073 - Properties dialog: make sorting by values work w/o CCE

[Don-vip]

Ticket #12079 has been marked as a duplicate of this ticket.