「イミテーションジュエリー」→ 「模倣品」や「偽物」というネガティブな印象を持たれがち。 @MarkusMeskanen: as the item is immutable, and when you mutated it in place you could not specialise it in the subclass. A further issue you could possibly think about, when you are unable to change the first kind, is extending the kind like so: 教育者，非为已往，专为将来。实现高水平科技自立自强，唯... https://www.slideshare.net/slideshow/aipl-lake-city-sector-103-gurgaon-exclusive-ultra-luxury-residences/283131693