- When there are multiple output bindings present and one of them defines
   a routing-key-expression, there is a bug that bypasses the code that skips
   the output conversion. This results in the framework attempts a pre-mature
   type conversion causing in later downstream errors. This happens because
   MessageConverterConfigurer tries to find a corresponding function for the
   entire function definition rather than using the individual function under
   consideraion. Fixing this issue by properly keeping track of the function
   name keyed off of the channel name, since channel name is what
   MessageConverterConfigurer uses to retrieve info about the function name.

Resolves spring-cloud#2847