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.
User can switch off source or sink behaviour (the default is to bind
to input and output streams), and then configure the name of a
supplier (for a source) or consumer (for a sink).
