Sorry, I don't see entire picture, but `AbstractMessageChannel#setConversionService` is `@Deprecated` in favor of `setMessageConverter`, which, in turn, is resolved as default `DefaultDatatypeChannelMessageConverter` from `BF`: https://github.com/spring-projects/spring-integration/pull/1053.
So, maybe there is a reason to rework it via registration the custom `Converter` with the existing `integrationConversionService` bean ?