Prototype-scoped bean injected into singleton behaves like a singleton

A @Scope("prototype") bean injected into a @Singleton bean via constructor or field injection is only created once — at singleton creation time. All subsequent calls share the same prototype instance, defeating the purpose of the prototype scope.

Use a scoped proxy or inject the ApplicationContext and look up the bean programmatically:

// Option 1: scoped proxy (preferred)
@Component
@Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE, proxyMode = ScopedProxyMode.TARGET_CLASS)
public class RequestState { ... }

// Option 2: ObjectFactory/Provider injection
@Service
public class OrderService {
    private final ObjectProvider<RequestState> stateProvider;

    public OrderService(ObjectProvider<RequestState> stateProvider) {
        this.stateProvider = stateProvider;
    }

    public void handle() {
        RequestState state = stateProvider.getObject(); // new instance each call
    }
}

Spring resolves and injects beans at context startup. A prototype bean injected at that point is resolved once and stored. The singleton retains a direct reference to that single instance for its lifetime.