Integration test of spring stream failed after update to Greenwich - spring-boot

Question

I just upgraded spring boot to 2.1.0.RELEASE and spring cloud stream to Greenwich.SR1.
I have an integration test which autowires MessageCollector, but the context fails to load because there is already a binder created in KafkaBinderConfiguration.
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.stream.test.binder.MessageCollector]: Factory method 'messageCollector' threw exception; nested exception is java.lang.ClassCastException: org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder cannot be cast to org.springframework.cloud.stream.test.binder.TestSupportBinder
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:620)
... 44 more
Caused by: java.lang.ClassCastException: org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder cannot be cast to org.springframework.cloud.stream.test.binder.TestSupportBinder
at org.springframework.cloud.stream.test.binder.MessageCollectorAutoConfiguration.messageCollector(MessageCollectorAutoConfiguration.java:35)
at org.springframework.cloud.stream.test.binder.MessageCollectorAutoConfiguration$$EnhancerBySpringCGLIB$$7750c59.CGLIB$messageCollector$0(<generated>)
at org.springframework.cloud.stream.test.binder.MessageCollectorAutoConfiguration$$EnhancerBySpringCGLIB$$7750c59$$FastClassBySpringCGLIB$$6fd994de.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363)
at org.springframework.cloud.stream.test.binder.MessageCollectorAutoConfiguration$$EnhancerBySpringCGLIB$$7750c59.messageCollector(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
... 45 more
There's TestSupportBinderConfiguration class which creates a test binder bean, but it's not happening because of its signature:
#Configuration
#ConditionalOnMissingBean(Binder.class)
public class TestSupportBinderConfiguration {}
Any ideas?