consider the following startup extension that replicate the ejb @Singleton @Startup behavior :

public class StartupExtension implements Extension
{
private final Set<Bean<?>> startupBeans = new LinkedHashSet<Bean<?>>();

<X> void processBean(@Observes ProcessBean<X> event)
{
if (event.getAnnotated().isAnnotationPresent(Startup.class) &&
event.getAnnotated().isAnnotationPresent(ApplicationScoped.class))

{ startupBeans.add(event.getBean()); }

}

void afterDeploymentValidation(@Observes AfterDeploymentValidation event, BeanManager manager)
{
for (Bean<?> bean : startupBeans)

{ // the call to toString() is a cheat to force the bean to be initialized manager.getReference(bean, bean.getBeanClass(), manager.createCreationalContext(bean)).toString(); }

}

}

in weld 2.0.0.Beta6 it will lead in an new IllegalStateException(METHOD_NOT_AVAILABLE_DURING_INITIALIZATION, methodName) exception (BeanManagerProxy::checkContainerInitialized)

though as https://issues.jboss.org/browse/CDI-315 suggests, it should not.