EDT violations

[GerdP]

What steps will reproduce the problem?

1. Start JOSM
2. Press Ctrl+L to download ​http://josm.openstreetmap.de/maps
3. Click OK on the popup that informs about missing white spaces

What is the expected result?

No EDT violations (and maybe also no popup?)

What happens instead?

Console shows several stack traces

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

Revision:17552
Is-Local-Build:true
Build-Date:2021-03-06 07:33:19

Identification: JOSM/1.5 (17552 SVN en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2004 (19041)
Memory Usage: 207 MB / 1972 MB (93 MB allocated, but free)
Java version: 15.0.1+9, AdoptOpenJDK, OpenJDK 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920×1080 (scaling 1,00×1,00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→32×32, 32×32→32×32
Program arguments: [--debug]

Plugins:
+ apache-commons (35524)
+ buildings_tools (35669)
+ ejml (35458)
+ geotools (35458)
+ imagery-xml-bounds (35640)
+ jaxb (35543)
+ jts (35458)
+ o5m (35640)
+ opendata (35640)
+ pbf (35708)
+ poly (35640)
+ reltoolbox (35640)
+ reverter (35688)
+ undelete (35640)
+ utilsplugin2 (35691)

Validator rules:
+ c:\josm\core\resources\data\validator\geometry.mapcss

Last errors/warnings:
- 00020,397 E: 	at org.openstreetmap.josm.plugins.imageryxmlbounds.io.JosmServerLocationReader.parseOsm(JosmServerLocationReader.java:34)
- 00020,397 E: 	at org.openstreetmap.josm.actions.downloadtasks.DownloadOsmTask$DownloadTask.parseDataSet(DownloadOsmTask.java:462)
- 00020,397 E: 	at org.openstreetmap.josm.actions.downloadtasks.DownloadOsmTask$DownloadTask.realRun(DownloadOsmTask.java:470)
- 00020,397 E: 	at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:94)
- 00020,397 E: 	at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:142)
- 00020,397 E: 	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
- 00020,397 E: 	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
- 00020,397 E: 	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
- 00020,398 E: 	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
- 00020,398 E: 	at java.base/java.lang.Thread.run(Thread.java:832)