Split Object (Alt+X) action sometimes adds multiple commands to stack

[GerdP]

What steps will reproduce the problem?

1. Have a split way and multipolygon in selection
2. Use Split Object to split the multipolygon
3. Undo

What is the expected result?

Step 2 should add one command to the command stack.
Step 3 should undo all changes.

What happens instead?

Step 2 may add up to three commands, one for each outer way that is split and one for the relation itself.
User has to find out how often Undo is needed.

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

Follow up of #18295. Similar problem when a single way is split with a split way.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-09-03 03:12:33 +0200 (Fri, 03 Sep 2021)
Build-Date:2021-09-03 01:31:19
Revision:18193
Relative:URL: ^/trunk

Identification: JOSM/1.5 (18193 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2009 (19043)
Memory Usage: 539 MB / 3641 MB (252 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 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
System property file.encoding: Cp1252
System property sun.jnu.encoding: Cp1252
Locale info: en_DE
Numbers with default locale: 1234567890 -> 1234567890
Dataset consistency test: No problems found

Plugins:
+ apache-commons (35524)
+ buildings_tools (35823)
+ contourmerge (v0.1.8)
+ ejml (35458)
+ geotools (35458)
+ imagery-xml-bounds (35723)
+ jaxb (35543)
+ jts (35458)
+ measurement (35640)
+ o5m (35640)
+ opendata (35803)
+ pbf (35825)
+ poly (35640)
+ reltoolbox (35829)
+ reverter (35732)
+ undelete (35640)
+ utilsplugin2 (35833)

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

[GerdP]

create single "Split Object" command, no new I18N string

[GerdP]

Unlike patch split_multipolygon_utilsplugin2_fix_2021-08-02.patch that was to attached in #18295 attachment:21491.patch​ also handles the case that a split way and a closed way is selected. The I18n string Split Multipolygon is removed.

[GerdP]

In 35842/osm:

fix #21491: Split Object (Alt+X) action sometimes adds multiple commands to stack
If multiple commands were generated, combine them into a single "Split Object" command