[PATCH][Github plugin](pt_assistant) plugin is able to lock up JOSM

[stefanct]

What steps will reproduce the problem?

0. Enable the offending plugin (pt_assistant at version 1ff2e15 in this case)
1. Open attached OSM
2. Press ctrl+shift+up

What is the expected result?

Execution of the validation routines etc., a warning window or the upload dialog.

What happens instead?

The window contents is not updated anymore and any further user input is ignored.

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

This happens with JOSM 18513 as well as an older 18303.
Without this specific plugin the upload works just fine.
In the past I have noticed some other problems with it (unhandled exceptions) but nothing as severe as this.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2022-07-07 23:02:39 +0200 (Thu, 07 Jul 2022)
Revision:18513
Build-Date:2022-07-08 01:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18513 en) Linux Debian GNU/Linux 10 (buster)
Memory Usage: 550 MB / 3928 MB (399 MB allocated, but free)
Java version: 11.0.15+10-post-Debian-1deb10u1, Debian, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 1600×900 (scaling 1.00×1.00) :0.1 2560×1440 (scaling 1.00×1.00)
Maximum Screen Size: 2560×1440
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_US.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_US
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: MATE
Java package: openjdk-11-jre:amd64-11.0.15+10-1~deb10u1
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-22+deb10u1
libcommons-compress-java: libcommons-compress-java:all-1.18-2+deb10u1
libcommons-logging-java: libcommons-logging-java:all-1.2-2
fonts-noto: fonts-noto:all-20181227-1
liboauth-signpost-java: liboauth-signpost-java:all-1.2.1.2-2
VM arguments: [-Djosm.restart=true, -Djava.net.useSystemProxies=true]

Plugins:
+ pt_assistant (1ff2e15)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/MountainbikeTrails&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Fahrradverleih&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/BicycleJunction&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Radwege&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/hiking_routes_with_trail_marking&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/SentieriItaliani&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Historical_Objects&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/MastAndTower&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Mountains&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Mountainbike&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/OpenStationMap&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Power_Mapping_Utility_Simple&zip=1
+ https://osmtools.de/josm/steps.xml

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1

Last errors/warnings:
- 00021.092 E: Broken tagging preset "bicycle_rental-Concretization for rental bikes" - number of items in 'display_values' must be the same as in 'values'
- 00021.093 E: Detailed information: [Lastenräder, eBikes, Fahrradanhänger] <> [cargo_bike, e-bikes, bike_trailer, yes]
- 00021.148 E: Broken tagging preset "public_transport-Public transport?" - number of items in 'display_values' must be the same as in 'values'
- 00021.149 E: Detailed information: [yes, no] <> [station]
- 00022.187 E: Failed to locate image 'bus.png'

[stefanct]

Deletion of a bus stop including its relation and membership in some routes

[stefanct]

I have attached the output of jstack.
This looks like a deadlock in the awt queue thread...

"AWT-EventQueue-0" #19 prio=6 os_prio=0 cpu=14574,27ms elapsed=103,27s allocated=609M defined_classes=2766 tid=0x00007f305802c000 nid=0x1fe in Object.wait()  [0x00007f3063a5d000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(java.base@11.0.15/Native Method)
	- waiting on <0x000000072b426e60> (a org.openstreetmap.josm.plugins.pt_assistant.actions.IncompleteMembersDownloadThread)
	at java.lang.Object.wait(java.base@11.0.15/Object.java:328)
	at org.openstreetmap.josm.plugins.pt_assistant.validation.PTAssistantValidatorTest.downloadIncompleteMembers(PTAssistantValidatorTest.java:212)
	- waiting to re-lock in wait() <0x000000072b426e60> (a org.openstreetmap.josm.plugins.pt_assistant.actions.IncompleteMembersDownloadThread)
	at org.openstreetmap.josm.plugins.pt_assistant.validation.PTAssistantValidatorTest.visit(PTAssistantValidatorTest.java:121)
	at org.openstreetmap.josm.data.osm.Relation.accept(Relation.java:176)
	at org.openstreetmap.josm.data.validation.Test.visit(Test.java:216)
	at org.openstreetmap.josm.actions.upload.ValidateUploadHook.checkUpload(ValidateUploadHook.java:66)
	at org.openstreetmap.josm.actions.UploadAction.lambda$checkPreUploadConditions$0(UploadAction.java:221)
...

[taylor.smock]

​https://github.com/JOSM/pt_assistant/pull/47