Update to sbt 1.2.8 (adding --ignore-source-errors for javadoc) (akka…

…#26233)

* Update to 1.2.8 and add --ignore-source-errors for javadoc

`--ignore-source-errors` makes 'sbt -Dakka.genjavadoc.enabled=true clean unidoc'
at least output something to target/javaunidoc, though AFAICS it is not
complete (missing index, CSS etc)

* Skip javadoc for scaladsl/GraphDSL.java

As problematic javadoc seems to be generated for
akka.stream.scaladsl.GraphDSL.Implicits.ReversePortsOps

* Enable frames again

project/AkkaBuild.scala

@@ -238,7 +238,7 @@ object AkkaBuild {
   lazy val docLintingSettings = Seq(
     javacOptions in compile ++= Seq("-Xdoclint:none"),
     javacOptions in test ++= Seq("-Xdoclint:none"),
-    javacOptions in doc ++= Seq("-Xdoclint:none"))
+    javacOptions in doc ++= Seq("-Xdoclint:none", "--ignore-source-errors"))
 
   def loadSystemProperties(fileName: String): Unit = {
     import scala.collection.JavaConverters._

project/Doc.scala

@@ -5,7 +5,7 @@
 package akka
 
 import sbt._
-import sbtunidoc.BaseUnidocPlugin.autoImport.{unidoc, unidocProjectFilter}
+import sbtunidoc.BaseUnidocPlugin.autoImport.{unidoc, unidocProjectFilter, unidocAllSources}
 import sbtunidoc.JavaUnidocPlugin.autoImport.JavaUnidoc
 import sbtunidoc.ScalaUnidocPlugin.autoImport.ScalaUnidoc
 import sbtunidoc.GenJavadocPlugin.autoImport._
@@ -115,7 +115,7 @@ object UnidocRoot extends AutoPlugin {
       .getOrElse(sbtunidoc.ScalaUnidocPlugin)
 
   val akkaSettings = UnidocRoot.CliOptions.genjavadocEnabled.ifTrue(
-    Seq(javacOptions in (JavaUnidoc, unidoc) := Seq("-Xdoclint:none"))).getOrElse(Nil)
+    Seq(javacOptions in (JavaUnidoc, unidoc) := Seq("-Xdoclint:none", "--frames", "--ignore-source-errors"))).getOrElse(Nil)
 
   override lazy val projectSettings = {
     def unidocRootProjectFilter(ignoreProjects: Seq[ProjectReference]): ProjectFilter = 
@@ -124,7 +124,13 @@ object UnidocRoot extends AutoPlugin {
     inTask(unidoc)(Seq(
       unidocProjectFilter in ScalaUnidoc := unidocRootProjectFilter(unidocRootIgnoreProjects.value),
       unidocProjectFilter in JavaUnidoc := unidocRootProjectFilter(unidocRootIgnoreProjects.value),
-      apiMappings in ScalaUnidoc := (apiMappings in (Compile, doc)).value))
+      apiMappings in ScalaUnidoc := (apiMappings in (Compile, doc)).value) ++
+      UnidocRoot.CliOptions.genjavadocEnabled.ifTrue(Seq(
+        // akka.stream.scaladsl.GraphDSL.Implicits.ReversePortsOps contains code that
+        // genjavadoc turns into (probably incorrect) Java code that in turn confuses the javadoc tool.
+        unidocAllSources in JavaUnidoc ~= { v => v.map(_.filterNot(_.getAbsolutePath.endsWith("scaladsl/GraphDSL.java"))) },
+      )).getOrElse(Nil)
+    )
   }
 }
 

project/build.properties

@@ -1,2 +1,2 @@
 # We need to fix javadoc generation to be able to update to 1.2.7, see https://github.com/akka/akka/issues/26100
-sbt.version=1.2.6
+sbt.version=1.2.8