How do ORM frameworks like Hibernate use the Proxy pattern for lazy loading of related entities?

When an entity has a relationship configured for lazy loading, Hibernate doesn't return the actual related entity when the parent object is loaded -- it returns a runtime-generated proxy object that implements the same type as the real entity but holds only its identifier. The proxy doesn't query the database at construction time. Only when a genuine field on that related entity is accessed does the proxy fire the actual query, fetch the real data, and delegate to it from then on. This lets an application load a parent object cheaply without pulling in every related entity up front, while code that accesses the relationship still works exactly as if it were holding the real entity the whole time -- the same lazy-loading and access-control ideas as the virtual proxy pattern, applied to database access.