RoutingServiceBuilder have moving parts that depend
on ordering to behave correctly. This leaves open potential for runtime
exceptions that could be caught at compile time.
RouteBuilder as all parameters are required and the
only be constructed within the finagle framework. Remove
RoutingServiceBuilder in favor of using
RouterBuilder directly, which in
turn simplifies the generic type signature that we need to carry, so we can
remove the need for
Route.transformed as a
replacement for the functionality of the
RouteBuilder and its transformed
result, so that we only need to be concerned with a
RequestTransformingFilter if the
RoutingService absolutely needs it.
Simpler generic type signatures, we are ensured that required items are
present when building a
RoutingService at compile time,
and we get to cut down on owned code as a result.
JIRA Issues: CSL-10111
Differential Revision: https://phabricator.twitter.biz/D543593