=htc improve error messages
+htp provide RoutingSettings through RequestContext
!htp consistently prefix simple extraction directives with `extract`
=str typos in returned types in javadsl
sadly a reflection based spec cannot easily test this
Merge pull request #16157 from spray/w/RequestContext-withChangedSettings

http: make RoutingSettings a property of the RequestContext
add Future case to javadsl.SinkTest
Merge branch 'fix-type-typos-javadsl-ktoso' into release-2.3-dev
=str removing duplicate fold sink definition on Sink
!str #16188 Remove value equality of iterable flow
!str #16066 rename connect to via/to

* add missing implicit conversions for ~>
* tests for all combinations when using ~>
Merge pull request #16177 from 2m/wip-16066-via-and-to

!str #16066 rename connect to via/to
Merge pull request #16189 from akka/wip-16188-rm-equalityValue-patriknw

!str #16188 Remove value equality of iterable flow
Merge pull request #16186 from ktoso/fix-remove-dup-fold-ktoso

=str removing duplicate fold sink definition on Sink
!str switch to a stable `Source.empty` val
=htc small fix and improvements to HttpEntity
!htc #15674 refactor, improve Multipart model
!htp #15674 upgrade to new Multipart model