Persistence of enum choices in Commands

[stefanhahmann]

With 664b3ab and 61e98d7 it was made possible to use enums with custom labels in scijava commands

However, currently enums with custom labels are not persisted, i.e. if the user makes some settings using an enum with custom labels in a dialog, closes this dialog and comes back to this dialog, the selected value would fall back to the default parameter instead of the last selected parameter, which users may consider a bug, since this behavior would be different to other parameter types.

[imagejan]

I think this issue is general for enums (i.e. not only enums with custom labels).

Looking at MoBIE's OpenCollectionTableCommand.DataRoot:
https://github.com/mobie/mobie-viewer-fiji/blob/18700b576efcc9574a9395598939bbf354f970e7/src/main/java/org/embl/mobie/command/open/OpenCollectionTableCommand.java#L49-L53

... non-default values seem to be correctly persisted to preference storage:

#@ PrefService ps
#@ ConvertService cs

import org.embl.mobie.command.open.OpenCollectionTableCommand
import org.embl.mobie.command.open.OpenCollectionTableCommand.DataRoot

stringValue = ps.get(OpenCollectionTableCommand.class, "dataRoot")

println(stringValue)  // e.g. UseTableFolder

converted = cs.convert(stringValue, DataRoot.class)

println(converted)  // e.g. UseTableFolder
println(converted.class)  // class org.embl.mobie.command.open.OpenCollectionTableCommand$DataRoot

However, the command dialog still falls back to default value every time.

Hence I think the issue is somewhere in the command module processing, not in the preferences.

@ctrueden would you have a best guess where to dig next?