IndexedDB with Java Patterns - Rich Domain Model

Product.java

package com.github.lofi.client;

public class Product {
	private final String id;
	private final String name;
	...

	private Product(Builder productBuilder) {
		this.id = productBuilder.id;
		this.name = productBuilder.name;
		...
	}

	public String getId() {
		return id;
	}

	public Integer getAmount() {
		return amount;
	}
	public Integer getPrice() {
		return price;
	}
	public Integer getCalculatedPriceWithAmount() {
		if (price == null || amount == null) {
			return 0;
		} else {
			return price * amount;
		}
	}

	public static class Builder {
		private final String id;
		private final String name;
		private String type;

		public Builder(String id, String name) {
			this.id = id;
			this.name = name;
		}

		public Builder setType(String type) {
			this.type = type;
			return this;
		}

		public Builder setAmount(Integer amount) {
			this.amount = amount;
			return this;
		}

		public Builder setPrice(Integer price) {
			this.price = price;
			return this;
		}

		public Product build() {
			Product product = new Product(this);
			return product;
		}
	}
}