Entities that use relationships often have dependencies on the existence of the other entity in the relationship. For example, a line item is part of an order, and if the order is deleted, then the line item should also be deleted. This is called a cascade delete relationship.
Cascade delete relationships are specified using the cascade=REMOVE element specification for @OneToOne and @OneToMany relationships. For example:
@OneToMany(cascade=REMOVE, mappedBy="customer") public Set<Order> getOrders() { return orders; }