GET /categories/1/items.json?select=ITEM_CD,ITEM_NAME
200 OK [{"ITEM_CD": "item1", "ITEM_NAME": "商品1"}, {"ITEM_CD": "item2", "ITEM_NAME": "商品2"}, {"ITEM_CD": "item3", "ITEM_NAME": "商品3"}]
商品情報を格納したJSON値を返します。