Flux.from() is cheap and can be used to marshal the inputs everywhere
internally. With this change users ought to be able to register any
function of any Publisher type.
This results in a better experience for users because the consumer
that they write is only applied to a Flux that is subscribed to
by the framework once. It gives better control over the flow of
foos, e.g. if some component wants to subscribe on a thread.
Makes it possible to support other "function" types in the future.
The user is always taking a risk with the lookup that the object
returned has the generic type desired (but that hasn't changed
with this commit). FunctionCatalog is a lot simpler as a result
and also a lot more flexible.
Should be easy enoug hto add back later, but it was causing issues
with type conversion where we are npot yet sophisticated enough
to chain functions together and keep track of the types being
passed between them.
Make it deployable via its maven coordinates in
spring-cloud-function-deployer (it is deployed by default on start
up right now, but that's just a demo)
