CollectionProperty inside another PropertyGroup

Question

I'm trying to initialize a PropertyGroup with pointers to objects inside another PropertyGroup. I'm getting an error: bpy_struct "ListItem" registration error: object_group could not register. Am I doing something wrong? In principle I'm trying to hold pointers to objects in a list, with each list with a label. Answer from here doesn't seem to be working:Register Object inside of Another Object

class ObjectPointer(PropertyGroup):

    obj: bpy.props.PointerProperty(type = bpy.types.Object)

class ListItem(PropertyGroup):

    name: StringProperty(
        name = "Name"
    )

    object_group: CollectionProperty(type = objectPointer)

Inside register():

bpy.types.Scene.my_list = CollectionProperty(type = ListItem)

Answer 1

Here is all you need to do:

class ObjectPointer(PropertyGroup):

    obj: bpy.props.PointerProperty(type = bpy.types.Object)

class ListItem(PropertyGroup):

    name: StringProperty(
        name = "Name"
    )

    object_group: CollectionProperty(type = ObjectPointer)

Inside register() - here are changes:

bpy.utils.register_class(ObjectPointer) #firstly register collection property type
bpy.utils.register_class(ListItem) #the one where you use ObjectPointer after
bpy.types.Scene.my_list = CollectionProperty(type = ListItem) #lastly assign