Can't convert Binder to KafkaMessageChannelBinder!!!!!!!

Iunconvertible types; cannot cast 'org.springframework.cloud.stream.binder.Binder<capture<?>,org.springframework.cloud.stream.binder.ConsumerProperties,org.springframework.cloud.stream.binder.ProducerProperties>' to 'org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder'

@Bean
public BinderCustomizer kafkaBinderCustomizer() {
    return (binder, binderName) -> {
        if (binder instanceof KafkaMessageChannelBinder) {
            KafkaMessageChannelBinder kafkaBinder = (KafkaMessageChannelBinder) binder;
        }
    };
}

When I debug the following code, the type of binder is KafkaMessageChannelBinder in debugger :)

@Bean
public BinderCustomizer kafkaBinderCustomizer() {
    return (binder, binderName) -> {
        System.out.println("hello world");
    };
}

Start with the BinderCustomizer callback and compare its Binder<?, ConsumerProperties, ProducerProperties> signature with KafkaMessageChannelBinder. Reproduce the compiler error from the shown configuration and inspect how the Kafka binder is exposed at runtime. Done means the documented customization path handles the Kafka binder without the reported incompatible cast.