[rules-users] collection question

[javaj]

I'm trying to write a rule to add an object to a collection if the collection
already contained a certain object with a specific attribute.

I developed a small example so maybe that will make more sense:

Use Case: In a product shipping applicaiton, anytime a product with the name
"cd1" is in the shipping order, a bonus product named "bonus_cd" needs to be
added to the shipping order.  The bonus cd should not be added if it's
already in the shipping order.

Shipping Order:

public class ShippingOrder {

	private Set<Product> products;
	
	public ShippingOrder() {}

	public Set<Product> getProducts() {
		return products;
	}

	public void setProducts(Set<Product> products) {
		this.products = products;
	}
		
}

Product:

public class Product {

	private String name;
	
	public Product(){}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
	
}


Rule:

rule "AddBonusCd"

	when
		$so : ShippingOrder()
		$productList : ArrayList(size == 1) from collect( Product(name matches
"cd1|bonus_cd") from $so.products)
	then
		System.out.println("Adding Bonus Cd");
		
		Set<Product> productSet = new HashSet<Product>($so.getProducts());
		
		Product bonusCd = new Product();
		bonusCd.setName("bonus_cd");
		productSet.add(bonusCd);
		
		modify($so) {
			setProducts(productSet);
		}
end

The Shipping Order object is inserted as the fact.

The rule is valid if only cd1 or cd_bonus is in the shipping order.  I only
want the rule to run when cd1 is in the product set but cd_bonus is not. 
Makes sense?

Thanks,
J
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