TrainGMMApp (strange name) fails with qgisdescriptor
### Description Dashboard is failing ``` ./bin/otbQgisDescriptor TrainGMMApp ./lib/otb/applications ./share/otb/description/ C:\dashboard\otb\superbuild_x64\OTB\build\bin\otbQgisDescriptor.exe TrainGMMApp C:/dashboard/otb/superbuild_x64/OTB/build/lib/otb/applications C:/dashboard/otb/superbuild_x64/OTB/build/share/otb/description/ ``` ERROR: default_value is empty for 'sample.edg' type='QgsProcessingParameterBoolean' ### Steps to reproduce `./bin/otbQgisDescriptor TrainGMMApp ./lib/otb/applications ./share/otb/description/` ### Configuration information https://dash.orfeo-toolbox.org/viewBuildError.php?buildid=318336
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