Here is the terminal output. I replaced my home directory with … in case you wonder.
ganttproject
WARNING: Unknown module: javafx.graphics specified to --add-exports
WARNING: Unknown module: javafx.controls specified to --add-exports
WARNING: Unknown module: javafx.graphics specified to --add-exports
WARNING: Unknown module: javafx.controls specified to --add-exports
WARNING: Unknown module: javafx.base specified to --add-exports
WARNING: Unknown module: javafx.controls specified to --add-exports
WARNING: Unknown module: javafx.graphics specified to --add-exports
WARNING: Unknown module: javafx.controls specified to --add-exports
WARNING: Unknown module: javafx.controls specified to --add-exports
WARNING: Unknown module: javafx.graphics specified to --add-exports
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime build
FINE: We will run with the following plugins:
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin biz.ganttproject.impex.msproject2-3.2.3240 at /usr/share/ganttproject/plugins/base/biz.ganttproject.impex.msproject2/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin org.ganttproject.chart.pert-3.2.3240 at /usr/share/ganttproject/plugins/base/org.ganttproject.chart.pert/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin biz.ganttproject.app.localization-3.2.3245 at /home/…/.ganttproject.d/updates/update-3245/biz.ganttproject.app.localization/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin biz.ganttproject.impex.ical-3.2.3240 at /usr/share/ganttproject/plugins/base/biz.ganttproject.impex.ical/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin org.ganttproject.impex.htmlpdf-3.2.3240 at /usr/share/ganttproject/plugins/base/org.ganttproject.impex.htmlpdf/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin net.sourceforge.ganttproject-3.2.3245 at /home/…/.ganttproject.d/updates/update-3245/ganttproject/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin biz.ganttproject.app.libs-3.2.3240 at /usr/share/ganttproject/plugins/base/biz.ganttproject.app.libs/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.ModuleRuntime lambda$build$3
FINE: Plugin biz.ganttproject.core-3.2.3240 at /usr/share/ganttproject/plugins/base/biz.ganttproject.core/plugin.xml
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.Runner run
FINE: Command line args: [-log, true, -log_file, /home/…/.ganttproject.d/logs/.ganttproject-20220721073446.log]
Jul 21, 2022 7:34:47 AM com.bardsoftware.eclipsito.runtime.Runner run
FINE: Launching application=net.sourceforge.ganttproject.GanttProject