@RestController
public class ProductController {
    private static final Map<String, Product> productMap = new HashMap<>();

    static {
        Stream.of(
                Product.of("B1", "Android Development (Java)", 380),
                Product.of("B2", "Android Development (Kotlin)", 420),
                Product.of("B3", "Data Structure (Java)", 250),
                Product.of("B4", "Finance Management", 450),
                Product.of("B5", "Human Resource Management", 330)
        ).forEach(p -> productMap.put(p.getId(), p));
    }

    // TODO
}