I have a file reference field
FileItem that has a display and description property but I want to add an extra one.
I was hoping I could just override the default widget but I can't use this to store data.
My next hope was to override the FileItem class and define the new property in schema() and propertyDefinitions() but that would mean I need a new FieldType.
I don't really want to create a new FieldType as I would need to migrate all of the data from the existing field.