Cross-build to Scala 2.13 (#228)

* Cross-build to Scala 2.13 #40

* formatting

* Fix JavaAkkaGrpcClientHelpers on 2.12

* --ignore-source-errors not needed after all

and is jdk11-only

.travis.yml

@@ -17,14 +17,14 @@ matrix:
 
 before_install: curl -Ls https://git.io/jabba | bash && . ~/.jabba/jabba.sh
 install: jabba install "adopt@~1.$TRAVIS_JDK.0-0" && jabba use "$_" && java -Xmx32m -version
-script: sbt headerCheck test:headerCheck scalafmtCheckAll scalafmtSbtCheck test paradox 
+script: sbt headerCheck test:headerCheck scalafmtCheckAll scalafmtSbtCheck test paradox ++2.13.1 test
 
 jobs:
   include:
 #   - stage: whitesource
 #     script: git branch -f "$TRAVIS_BRANCH" && git checkout "$TRAVIS_BRANCH" && sbt whitesourceCheckPolicies whitesourceUpdate
     - stage: publish
-      script: sbt +publish
+      script: sbt ++2.12.8 publish ++2.13.1 publish
     - stage: techhub-ping
       script: curl -I https://ci.lightbend.com/job/techhub-publisher/build?token=$TECH_HUB_TOKEN
 

build.sbt

@@ -1,4 +1,5 @@
 import build.play.grpc.Dependencies
+import build.play.grpc.Dependencies.Versions.scala212
 import build.play.grpc.ProjectExtensions.AddPluginTest
 
 ThisBuild / organization := "com.lightbend.play"
@@ -86,6 +87,8 @@ val playGenerators = Project("play-grpc-generators", file("play-generators"))
       Dependencies.Compile.akkaGrpcCodegen,
       Dependencies.Test.scalaTest,
     ),
+    // Only used in build tools (like sbt), so only 2.12 is needed:
+    crossScalaVersions := Seq(scala212),
   )
 
 val playTestkit = Project("play-grpc-testkit", file("play-testkit"))

play-testkit/src/main/java/play/grpc/testkit/JavaAkkaGrpcClientHelpers.java

@@ -46,7 +46,11 @@ public static ServerEndpoint getHttp2Endpoint(final ServerEndpoints serverEndpoi
       // the user set
       // `akka.grpc.client."".use-tls` to false for gRPC so this should return the non-TLS HTTP/2
       // endpoint on the list.
-      return possibleEndpoints.filter(endpoint -> endpoint.ssl().isDefined()).head();
+      final scala.collection.Iterable<ServerEndpoint> sslEndpoints =
+          possibleEndpoints
+	    .filter(endpoint -> endpoint.ssl().isDefined())
+            .toIterable();
+      return sslEndpoints.head();
     }
   }
 

project/CommonPlugin.scala

@@ -1,5 +1,9 @@
+package build.play.grpc
+
 import sbt._
 import sbt.Keys._
+import Dependencies.Versions.scala212
+import Dependencies.Versions.scala213
 
 // WORKAROUND https://github.com/sbt/sbt/issues/2899
 object CommonPlugin extends AutoPlugin {
@@ -12,6 +16,8 @@ object CommonPlugin extends AutoPlugin {
       else
         Nil
     },
+    javacOptions in doc --= Seq("-Xlint:unchecked", "-Xlint:deprecation"),
+    crossScalaVersions := Seq(scala212, scala213),
   )
 
   val scalaVersionNumber = Def.setting(VersionNumber(scalaVersion.value))

project/Dependencies.scala

@@ -6,6 +6,9 @@ import sbt.Keys._
 object Dependencies {
 
   object Versions {
+    val scala212 = "2.12.8"
+    val scala213 = "2.13.1"
+
     val akka = "2.6.4"
 
     val akkaGrpc = "0.8.1" // TODO: obtain via sbt-akka-grpc?