def METHOD_NAME(container_provider: ContainerProvider, upgrade_manager: VersionUpgradeManager) -> ContainerProvider:
    my_folder = os.path.dirname(os.path.abspath(__file__))
    definition_ids = {"basic_definition", "children", "functions", "inherits", "metadata_definition", "multiple_settings", "single_setting"}
    for definition_id in definition_ids:
        container = DefinitionContainer(definition_id)
        container.deserialize(open(os.path.join(my_folder, "definitions", definition_id + ".def.json"), encoding = "utf-8").read())
        container_provider._containers[definition_id] = container
        container_provider.addMetadata(container.getMetaData())
    instance_ids = {"basic_instance", "metadata_instance", "setting_values"}
    for instance_id in instance_ids:
        container = UM.Settings.InstanceContainer.InstanceContainer(instance_id)
        container.deserialize(open(os.path.join(my_folder, "instances", instance_id + ".inst.cfg"), encoding = "utf-8").read())
        container_provider._containers[instance_id] = container
        container_provider.addMetadata(container.getMetaData())
    return container_provider