Merge branch 'stable-3.8' into master

* stable-3.8:
  Use orNull instead of explicit null default
  Fix IterableOnce foreach deprecation warning
  Fix array splat deprecation warning
  Fix .toStream deprecation warning
  Fix deprecated `l` for Longs
  Remove use of deprecated JavaConverters class
  Fix TraversableOnce deprecation warnings
  Fix procedure syntax deprecation warnings
  Fix reflective structural type access warning
  Fix unable to check type warnings
  Fix override without parameter list warning
  Update Scala to 2.13.10
  Bump scalatest to 3.2.16
  Fix feature warnings
  Bump sbt to 1.8.3
  Add gitignore entries
  Use pattern matching over asInstanceOf in test
  Add `UseLocalDisk` annotation to fix test
  Bump Gerrit API to 3.8.0-rc4
  Remove unused test method
  Set Gerrit to v3.6.0-rc0

Change-Id: I8c0884831ae33838f7f359450c5810efb99a09fc

build.sbt

diff --git a/build.sbt b/build.sbt
index 5203e12..46b0942 100644
--- a/build.sbt
+++ b/build.sbt
@@ -13,7 +13,6 @@
 lazy val root = (project in file("."))
   .settings(
     name := pluginName,
-    resolvers += Resolver.mavenLocal,
     version := gerritApiVersion,
 
     scalaVersion := "2.13.10",

src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedCommitHistogram.scala

diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedCommitHistogram.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedCommitHistogram.scala
index f39fc73..2d30b47 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedCommitHistogram.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedCommitHistogram.scala
@@ -28,7 +28,7 @@
   extends CommitHistogram {
 
   def includeWithBranches(commit: RevCommit, user: PersonIdent, branches: Set[String]): Unit = {
-    for (branch <- branches) {
+    branches.foreach { branch =>
       val originalStrategy = aggregationStrategy
       this.aggregationStrategy = BY_BRANCH(branch, aggregationStrategy)
       this.include(commit, user)