grappelli NestedTabularInline.classes collapsible inlines don't work

[luxoar]

An instance of a nested InlineModel cannot be edited when using grapelli, collapsed classes and NestedTabularInline.

class DocumentInline(nested_admin.NestedTabularInline):
    model = Document
    extra = 0
    fields = ['document_type', 'file']
    classes = ('grp-collapse grp-closed',)

class ProjectInline(nested_admin.NestedStackedInline):
    model = Project
    inlines = ['DocumentInline']

class UserAdmin(nested_admin.NestedModelAdmin):
    model = User
    inlines = ['ProjectInline']

Results in this:

The fields are not editable.

Without classes attribute in DocumentInline: