When ReactiveMessageHandler support was introduced into ReactiveStreamsConsumer, MockIntegrationContext logic wasn't adjusted respectively.

[liam33893]

In what version(s) of Spring Integration are you seeing this issue?
5.5.15

Describe the bug

When ReactiveMessageHandler support was introduced into ReactiveStreamsConsumer, MockIntegrationContext logic wasn't adjusted respectively.

To Reproduce

Try to use reactive endpoint with MockIntegrationContext

Sample

Full info in the Stackoverflow issue -
spring-integration MockIntegrationContext ReactiveStreamConsumer: IllegalArgumentException: 'subscriber' must not be null in the "...endpoint"

Thanks in advance!