pjfanning opened a new pull request, #1379:
URL: https://github.com/apache/pekko-http/pull/1379
### Motivation
Java generics are invariant, so a Java caller holding a `List<RawHeader>`
(or any other collection of an `HttpHeader` subtype) cannot pass it to Java API
methods that take `Iterable<HttpHeader>`. They have to copy or cast it first.
This is suggested PR 1 of #1378.
### Modification
Widen the headers parameter to `Iterable<? extends HttpHeader>`
(`java.lang.Iterable[? <: HttpHeader]` in Scala) in:
- `HttpMessage.MessageTransformations.addHeaders` / `withHeaders` (so
`HttpRequest` / `HttpResponse`), plus the matching scaladsl `HttpMessage`
implementations
- the six `RouteDirectives.complete(..., headers, ...)` overloads
- `Marshaller.entityToResponse` and `Marshaller.entityToOKResponse`
The Scala code that converts the headers upcasts the wildcard `Iterable`
before the existing `asScala` conversion. `java.lang.Iterable` is read-only, so
the upcast is safe.
MiMa reports `IncompatibleSignatureProblem` for these methods because the
generic signature changed. The erased JVM signatures are unchanged, so existing
compiled callers still link and existing Java sources still compile. The
excludes are in new `java-iterable-http-header-wildcard.excludes` files in
`http-core` and `http`.
One edge case is a third-party Scala class implementing
`HttpMessage.MessageTransformations` directly. Such a class would need to
update its override signature. This should be rare, since the interface exists
for `HttpRequest` / `HttpResponse`.
No docs change: the methods behave the same, they just accept more argument
types.
### Result
Java callers can pass collections of any `HttpHeader` subtype to these
methods.
### Tests
- `sbt "http-core/Test/testOnly
org.apache.pekko.http.javadsl.model.HttpMessageTest" "http-tests/Test/testOnly
org.apache.pekko.http.javadsl.server.directives.RouteDirectivesTest"`: passed
on Scala 2.13 and 3.3.8
- new `HttpMessageTest` case: `addHeaders` / `withHeaders` with a
`List<RawHeader>`
- new `RouteDirectivesTest` case: every changed `complete` overload, plus
`Marshaller.entityToResponse` / `entityToOKResponse`, with a `List<RawHeader>`,
checking status, header and entity
- both tests fail to compile against the old signatures
- `sbt http-core/mimaReportBinaryIssues http/mimaReportBinaryIssues`: passed
with the new excludes
- `sbt docs/Test/compile`: passed
- `scalafmtCheckAll`, `javafmtCheck` (JDK 17) and `headerCheckAll` on the
changed modules: passed
### References
Refs #1378
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