Delete a POJO entity couldn't automatically delete associated blob file for multiple image

[leeaee]

1. Create a multiple image class.
2. Upload multiple images one time.
3. Try to delete multiple images POJO entity, expect automatically delete associated blob files, but failed.

Code:
MultipleImage.class

@Store("store:image")
@Entity("image")
public class MultipleImage extends MorphiaAdaptiveRecord<Image> implements SimpleBean {
    public String title;
    @Store
    public List<ISObject> images;
    public Image() {}
    public Image(String title, List<ISObject> images) {
        this.title = title;
        this.images = images;
    }
}

@UrlContext("/api/upload")
public class UploadEndpoint {
    @Inject
    private MorphiaDao<MultipleImage> dao;

    ...

    @DeleteAction("image/{id}")
    public void delete(@NotNull String id) {
        MultipleImage image = dao.findById(id);
        notFoundIfNull(image);
        dao.delete(image);
    }
}