Attempting to use Collectors.toMap() function not working for collection of Products

I have a collection of Products that I want to transform into a HashMap based on the productCode, which is an identifier in the Product object. However, it does not seem to work, from following examples I saw. Can someone point out what I’m doing wrong?
Here is the code in it’s entirety:

    import lombok.Builder;
    import lombok.Data;

    import java.math.BigDecimal;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.Objects;
    import java.util.stream.Collectors;
    import static java.util.function.UnaryOperator.identity;
 

    @Data
    public class Product {
      private String productCode;
      private String productDescription;
      private BigDecimal unitCost;
      private BigDecimal bulkPrice;
    
      @Builder
      public Product(String productCode, String productDescription, BigDecimal unitCost, 
   BigDecimal bulkPrice) {
        this.productCode = productCode;
        this.productDescription = productDescription;
        this.unitCost = unitCost;
        this.bulkPrice = bulkPrice;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Product product = (Product) o;
        return Objects.equals(productCode, product.productCode);
    }

    @Override
    public int hashCode() {
        return Objects.hash(productCode);
    }

    public static void main(String[] args) {
        List<Product> products = new ArrayList<>();
        Product musk1  = new Product("FRAGMusk001", "Men's fragrance", BigDecimal.valueOf(9.00), BigDecimal.valueOf(7.99));
        Product musk2 = new Product("FRAGMusk001", "Men's fragrance", BigDecimal.valueOf(9.00), BigDecimal.valueOf(7.99));
        Product dior = new Product("FRAGDior877", "Men's mid range cologne", BigDecimal.valueOf(9.00), BigDecimal.valueOf(7.99));
        Product paccoRabane = new Product("FRAGRabbne442", "Men's mid range cologne", BigDecimal.valueOf(9.00), BigDecimal.valueOf(7.99));
        Product verricio = new Product("FRAGVeri556", "Men's elite cologne", BigDecimal.valueOf(9.00), BigDecimal.valueOf(7.99));
        products.add(musk1);
        products.add(musk2);
        products.add(dior);
        products.add(paccoRabane);
        products.add(verricio);
        // This does not work
        Map<String, Product> productMap = products.stream().distinct().collect(Collectors.toMap(product -> product.getProductCode()));, identity()));
    }
}

>Solution :

product.getProduct() isn’t a method in product. Presumably you meant product -> product.getProductCode(), or simpler: Product::getProductCode.

Note that you don’t have to write that equals and hashcode method; just stick @EqualsAndHashCode.Include on your productCode field and delete hashCode and equals – then lombok will take care of it for you.