Delete a Product (DELETE) in Java

The shop stops selling the Gift card. To remove a product, a client sends a DELETE to the product's own path, /products/8: the third method on that path, after GET and PUT. It needs no body: the id in the path says it all.

Here is a DELETE on another table, a list of newsletter subscribers:

int count = db.update("DELETE FROM subscribers WHERE id = ?", 3);
System.out.println(count);   // 1 if subscriber 3 was there, 0 if not

The WHERE matters even more than in an UPDATE: DELETE FROM products alone empties the whole table. Deleting an id that isn't there is no error, it just removes nothing, so db.update answers 0 and you answer 404. When a product is removed, you answer 204 No Content with an empty body: it worked, and there is nothing to send back.

Starting from the shop's 8 products, your code must answer, in this order:

DELETE /products/8  →  204  (empty body)
GET /products/8  →  404  {"error": "Product not found"}
DELETE /products/8  →  404  {"error": "Product not found"}
DELETE /products/99  →  404  {"error": "Product not found"}

Your task: add DELETE /products/{productId} with the method deleteProduct. Delete that product with a ? placeholder. Answer 404 if no row was removed, and otherwise an empty answer with the status 204.

Assignment
Follow the Coding Tutorial to add the deleteProduct method, which removes a product from the database.

Hint
db.update takes the SQL, then the value for its ?: pass productId right after the SQL. For the 204, ResponseEntity.noContent() sets the status, and build() makes an answer with no body.