@Configuration class with this to enable proxying
@RabbitListener beans to capture arguments and result (if any).RabbitListenerTestHarness.RabbitListenerAnnotationBeanPostProcessor.RabbitListenerConfigurationSelector extension to register
a RabbitListenerTestBootstrap, but already with the higher order,
so the RabbitListenerTestHarness bean is registered earlier,
than RabbitListenerAnnotationBeanPostProcessor.RabbitTemplate that invokes @RabbitListener s directly.