diff --git a/.gitignore b/.gitignore
index f81b8e9..da80ec3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,5 +2,8 @@
 .project
 .classpath
 .settings/
+.vscode
+.bsp
 target/
 /bin/
+/project/project
diff --git a/build.sbt b/build.sbt
index f34f073..6f5750d 100644
--- a/build.sbt
+++ b/build.sbt
@@ -8,13 +8,15 @@
 
 concurrentRestrictions in Global += Tags.limit(Tags.Test, 1)
 
+ThisBuild / scalacOptions ++= Seq("-deprecation", "-feature")
+
 lazy val root = (project in file("."))
   .settings(
     name := pluginName,
     resolvers += Resolver.mavenLocal,
     version := gerritApiVersion,
 
-    scalaVersion := "2.11.12",
+    scalaVersion := "2.13.10",
 
     libraryDependencies ++= Seq(
       "io.fabric8" % "gitective-core" % "0.9.54"
@@ -28,12 +30,12 @@
 
       "com.google.gerrit" % "gerrit-acceptance-framework" % gerritApiVersion % Test,
       "org.bouncycastle" % "bcpg-jdk15on" % "1.61" % Test,
-      "org.scalatest" %% "scalatest" % "3.0.1" % Test,
+      "org.scalatest" %% "scalatest" % "3.2.16" % Test,
       "net.codingwell" %% "scala-guice" % "5.0.0" % Test),
 
-    assemblyJarName in assembly := s"$pluginName.jar",
+    assembly / assemblyJarName := s"$pluginName.jar",
 
-    packageOptions in(Compile, packageBin) += Package.ManifestAttributes(
+    Compile / packageBin / packageOptions += Package.ManifestAttributes(
       ("Gerrit-ApiType", "plugin"),
       ("Gerrit-PluginName", pluginName),
       ("Gerrit-Module", "com.googlesource.gerrit.plugins.analytics.Module"),
diff --git a/project/build.properties b/project/build.properties
index 0cd8b07..72413de 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.2.3
+sbt.version=1.8.3
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
index 98e4e06..5b4f172 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
@@ -24,6 +24,8 @@
 import com.googlesource.gerrit.plugins.analytics.common._
 import org.kohsuke.args4j.{Option => ArgOption}
 
+import scala.util.Using
+
 @CommandMetaData(name = "contributors", description = "Extracts the list of contributors to a project")
 class ContributorsCommand @Inject()(val executor: ContributorsService,
                                     val projects: ProjectsCollection,
@@ -42,9 +44,9 @@
 
   @ArgOption(name = "--since", aliases = Array("--after", "-b"),
     usage = "(included) begin timestamp. Must be in the format 2006-01-02[ 15:04:05[.890][ -0700]]")
-  def setBeginDate(date: String) {
+  def setBeginDate(date: String) = {
     try {
-      beginDate = Some(date)
+      beginDate = Some(date.isoStringToLongDate)
     } catch {
       case e: Exception => throw die(s"Invalid begin date ${e.getMessage}")
     }
@@ -52,9 +54,9 @@
 
   @ArgOption(name = "--until", aliases = Array("--before", "-e"),
     usage = "(excluded) end timestamp. Must be in the format 2006-01-02[ 15:04:05[.890][ -0700]]")
-  def setEndDate(date: String) {
+  def setEndDate(date: String) = {
     try {
-      endDate = Some(date)
+      endDate = Some(date.isoStringToLongDate)
     } catch {
       case e: Exception => throw die(s"Invalid end date ${e.getMessage}")
     }
@@ -62,7 +64,7 @@
 
   @ArgOption(name = "--aggregate", aliases = Array("-g"),
     usage = "Type of aggregation requested. ")
-  def setGranularity(value: String) {
+  def setGranularity(value: String) = {
     try {
       granularity = Some(AggregationStrategy.apply(value))
     } catch {
@@ -88,9 +90,9 @@
 
   @ArgOption(name = "--since", aliases = Array("--after", "-b"), metaVar = "QUERY",
     usage = "(included) begin timestamp. Must be in the format 2006-01-02[ 15:04:05[.890][ -0700]]")
-  def setBeginDate(date: String) {
+  def setBeginDate(date: String) = {
     try {
-      beginDate = Some(date)
+      beginDate = Some(date.isoStringToLongDate)
     } catch {
       case e: Exception => throw new BadRequestException(s"Invalid begin date ${e.getMessage}")
     }
@@ -98,9 +100,9 @@
 
   @ArgOption(name = "--until", aliases = Array("--before", "-e"), metaVar = "QUERY",
     usage = "(excluded) end timestamp. Must be in the format 2006-01-02[ 15:04:05[.890][ -0700]]")
-  def setEndDate(date: String) {
+  def setEndDate(date: String) = {
     try {
-      endDate = Some(date)
+      endDate = Some(date.isoStringToLongDate)
     } catch {
       case e: Exception => throw new BadRequestException(s"Invalid end date ${e.getMessage}")
     }
@@ -108,7 +110,7 @@
 
   @ArgOption(name = "--granularity", aliases = Array("--aggregate", "-g"), metaVar = "QUERY",
     usage = "can be one of EMAIL, EMAIL_HOUR, EMAIL_DAY, EMAIL_MONTH, EMAIL_YEAR, defaulting to EMAIL")
-  def setGranularity(value: String) {
+  def setGranularity(value: String) = {
     try {
       granularity = Some(AggregationStrategy.apply(value))
     } catch {
@@ -137,15 +139,15 @@
 
   def get(projectRes: ProjectResource, startDate: Option[Long], stopDate: Option[Long],
           aggregationStrategy: AggregationStrategy, extractBranches: Boolean)
-  : TraversableOnce[UserActivitySummary] = {
+  : IterableOnce[UserActivitySummary] = {
 
-    ManagedResource.use(repoManager.openRepository(projectRes.getNameKey)) { repo =>
+    Using.resource(repoManager.openRepository(projectRes.getNameKey)) { repo =>
       val stats = new Statistics(projectRes.getNameKey, commitsStatisticsCache)
       val branchesExtractor = extractBranches.option(new BranchesExtractor(repo))
 
       histogram.get(repo, new AggregatedHistogramFilterByDates(startDate, stopDate, branchesExtractor, aggregationStrategy))
         .flatMap(aggregatedCommitActivity => UserActivitySummary.apply(stats)(aggregatedCommitActivity))
-        .toStream
+        .to(LazyList)
     }
   }
 }
@@ -178,7 +180,7 @@
   def apply(statisticsHandler: Statistics)(uca: AggregatedUserCommitActivity)
   : Iterable[UserActivitySummary] = {
 
-    statisticsHandler.forCommits(uca.getIds: _*).map { stat =>
+    statisticsHandler.forCommits(uca.getIds.toIndexedSeq: _*).map { stat =>
       val maybeBranches =
         uca.key.branch.fold(Array.empty[String])(Array(_))
 
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Module.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Module.scala
index b0c643e..a57ebac 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Module.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Module.scala
@@ -22,7 +22,7 @@
 
 class Module extends AbstractModule {
 
-  override protected def configure() {
+  override protected def configure() = {
     bind(classOf[BotLikeExtractor]).to(classOf[BotLikeExtractorImpl])
 
     install(new CommitsStatisticsCacheModule())
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/SshModule.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/SshModule.scala
index 48a48b4..01fe36d 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/SshModule.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/SshModule.scala
@@ -18,7 +18,7 @@
 
 class SshModule extends PluginCommandModule {
 
-  override protected def configureCommands {
+  override protected def configureCommands = {
     command(classOf[ContributorsCommand])
   }
 }
\ No newline at end of file
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedHistogramFilterByDates.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedHistogramFilterByDates.scala
index bc1315e..305c388 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedHistogramFilterByDates.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/AggregatedHistogramFilterByDates.scala
@@ -29,7 +29,7 @@
     val commitDate = commit.getCommitterIdent.getWhen.getTime
     val author = commit.getAuthorIdent
 
-    if (from.fold(true)(commitDate >=) && to.fold(true)(commitDate <)) {
+    if (from.fold(true)(commitDate >= _) && to.fold(true)(commitDate < _)) {
       if(branchesExtractor.isDefined) {
         val branches = branchesExtractor.get.branchesOfCommit(commit.getId)
         getHistogram.includeWithBranches(commit, author, branches)
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractor.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractor.scala
index 9703da1..1725835 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractor.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractor.scala
@@ -14,28 +14,27 @@
 
 package com.googlesource.gerrit.plugins.analytics.common
 
-import com.googlesource.gerrit.plugins.analytics.common.ManagedResource.use
 import org.eclipse.jgit.api.Git
 import org.eclipse.jgit.lib.{Constants, ObjectId, Repository}
 import org.eclipse.jgit.revwalk.RevWalk
 
-import scala.collection.JavaConversions._
+import scala.jdk.CollectionConverters._
+import scala.util.Using
 
 case class BranchesExtractor(repo: Repository) {
   lazy val branchesOfCommit: Map[ObjectId, Set[String]] = {
 
-    use(new Git(repo)) { git =>
-      git.branchList.call.foldLeft(Map.empty[ObjectId, Set[String]]) { (branchesAcc, ref) =>
+    Using.resources(new Git(repo), new RevWalk(repo)) { (git, rw) =>
+      git.branchList.call.asScala.foldLeft(Map.empty[ObjectId, Set[String]]) { (branchesAcc, ref) =>
         val branchName = ref.getName.drop(Constants.R_HEADS.length)
 
-        use(new RevWalk(repo)) { rw: RevWalk =>
-          rw.markStart(rw.parseCommit(ref.getObjectId))
-          rw.foldLeft(branchesAcc) { (thisBranchAcc, rev) =>
-            val sha1 = rev.getId
-            thisBranchAcc.get(sha1) match {
-              case Some(set) => thisBranchAcc + (sha1 -> (set + branchName))
-              case None      => thisBranchAcc + (sha1 -> Set(branchName))
-            }
+        rw.reset()
+        rw.markStart(rw.parseCommit(ref.getObjectId))
+        rw.asScala.foldLeft(branchesAcc) { (thisBranchAcc, rev) =>
+          val sha1 = rev.getId
+          thisBranchAcc.get(sha1) match {
+            case Some(set) => thisBranchAcc + (sha1 -> (set + branchName))
+            case None      => thisBranchAcc + (sha1 -> Set(branchName))
           }
         }
       }
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/CommitsStatisticsLoader.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/CommitsStatisticsLoader.scala
index 6adb617..e4dbe11 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/CommitsStatisticsLoader.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/CommitsStatisticsLoader.scala
@@ -21,14 +21,14 @@
 import com.google.gerrit.server.project.ProjectCache
 import com.google.inject.Inject
 import com.googlesource.gerrit.plugins.analytics.{AnalyticsConfig, CommitInfo, IssueInfo}
-import com.googlesource.gerrit.plugins.analytics.common.ManagedResource.use
 import org.eclipse.jgit.diff.{DiffFormatter, RawTextComparator}
 import org.eclipse.jgit.revwalk.RevWalk
 import org.eclipse.jgit.treewalk.{CanonicalTreeParser, EmptyTreeIterator}
 import org.eclipse.jgit.util.io.DisabledOutputStream
-import scala.compat.java8.OptionConverters._
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
+import scala.jdk.OptionConverters._
+import scala.util.Using
 import scala.util.matching.Regex
 
 class CommitsStatisticsLoader @Inject() (
@@ -38,6 +38,7 @@
   config: AnalyticsConfig,
   ignoreFileSuffixFilter: IgnoreFileSuffixFilter
 ) extends CacheLoader[CommitsStatisticsCacheKey, CommitsStatistics] {
+  import CommitsStatisticsLoader._
 
   override def load(cacheKey: CommitsStatisticsCacheKey): CommitsStatistics = {
     import RevisionBrowsingSupport._
@@ -45,52 +46,52 @@
     val objectId = cacheKey.commitId
     val nameKey = Project.nameKey(cacheKey.projectName)
     val commentInfoList: Seq[CommentLinkInfo] =
-      if(config.isExtractIssues) projectCache.get(nameKey).asScala.toList.flatMap(_.getCommentLinks.asScala) else Seq.empty
+      if(config.isExtractIssues) projectCache.get(nameKey).toScala.toList.flatMap(_.getCommentLinks.asScala) else Seq.empty
     val replacers = commentInfoList.map(info =>
       Replacer(
         info.`match`.r,
         Option(info.link).getOrElse(info.html)))
 
-    use(gitRepositoryManager.openRepository(nameKey)) { repo =>
+    Using.Manager { use =>
+      val repo = use(gitRepositoryManager.openRepository(nameKey))
 
       // I can imagine this kind of statistics is already being available in Gerrit but couldn't understand how to access it
       // which Injection can be useful for this task?
-        use(new RevWalk(repo)) { rw =>
-          val reader = repo.newObjectReader()
-          val commit = rw.parseCommit(objectId)
-          val commitMessage = commit.getFullMessage
+      val rw = use(new RevWalk(repo))
+      val reader = repo.newObjectReader()
+      val commit = rw.parseCommit(objectId)
+      val commitMessage = commit.getFullMessage
 
-          val oldTree = {
-            // protects against initial commit
-            if (commit.getParentCount == 0)
-              new EmptyTreeIterator
-            else
-              new CanonicalTreeParser(null, reader, rw.parseCommit(commit.getParent(0).getId).getTree)
-          }
+      val oldTree = {
+        // protects against initial commit
+        if (commit.getParentCount == 0)
+          new EmptyTreeIterator
+        else
+          new CanonicalTreeParser(null, reader, rw.parseCommit(commit.getParent(0).getId).getTree)
+      }
 
-          val newTree = new CanonicalTreeParser(null, reader, commit.getTree)
+      val newTree = new CanonicalTreeParser(null, reader, commit.getTree)
 
-          val df = new DiffFormatter(DisabledOutputStream.INSTANCE)
-          df.setRepository(repo)
-          df.setPathFilter(ignoreFileSuffixFilter)
-          df.setDiffComparator(RawTextComparator.DEFAULT)
-          df.setDetectRenames(true)
-          val diffs = df.scan(oldTree, newTree).asScala
+      val df = new DiffFormatter(DisabledOutputStream.INSTANCE)
+      df.setRepository(repo)
+      df.setPathFilter(ignoreFileSuffixFilter)
+      df.setDiffComparator(RawTextComparator.DEFAULT)
+      df.setDetectRenames(true)
+      val diffs = df.scan(oldTree, newTree).asScala
 
-          val lines = (for {
-            diff <- diffs
-            edit <- df.toFileHeader(diff).toEditList.asScala
-          } yield Lines(edit.getEndA - edit.getBeginA, edit.getEndB - edit.getBeginB)).fold(Lines(0, 0))(_ + _)
+      val lines = (for {
+        diff <- diffs
+        edit <- df.toFileHeader(diff).toEditList.asScala
+      } yield Lines(edit.getEndA - edit.getBeginA, edit.getEndB - edit.getBeginB)).fold(Lines(0, 0))(_ + _)
 
-          val files: Set[String] = diffs.map(df.toFileHeader(_).getNewPath).toSet
+      val files: Set[String] = diffs.map(df.toFileHeader(_).getNewPath).toSet
 
-          val commitInfo = CommitInfo(objectId.getName, commit.getAuthorIdent.getWhen.getTime, commit.isMerge, botLikeExtractor.isBotLike(files), files)
-          val commitsStats = CommitsStatistics(lines.added, lines.deleted, commitInfo.merge, commitInfo.botLike, List(commitInfo), extractIssues(commitMessage, replacers).toList)
+      val commitInfo = CommitInfo(objectId.getName, commit.getAuthorIdent.getWhen.getTime, commit.isMerge, botLikeExtractor.isBotLike(files), files)
+      val commitsStats = CommitsStatistics(lines.added, lines.deleted, commitInfo.merge, commitInfo.botLike, List(commitInfo), extractIssues(commitMessage, replacers).toList)
 
-          commitsStats
-        }
+      commitsStats
     }
-  }
+  }.get
 
   private def extractIssues(commitMessage: String, replacers: Seq[Replacer]): Seq[IssueInfo] =
     replacers.flatMap {
@@ -101,9 +102,9 @@
             IssueInfo(code, transformed)
           })
     }
+}
 
-
-
+object CommitsStatisticsLoader {
   final private case class Replacer(pattern: Regex, replaced: String)
 
   final private case class Lines(deleted: Int, added: Int) {
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/DateConversions.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/DateConversions.scala
index 874dc0d..4bf7dfe 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/DateConversions.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/DateConversions.scala
@@ -18,5 +18,7 @@
 
 object DateConversions {
 
-  implicit def isoStringToLongDate(s: String): Long = JavaSqlTimestampHelper.parseTimestamp(s).getTime
+  implicit class StringOps(val s: String) extends AnyVal {
+    def isoStringToLongDate: Long = JavaSqlTimestampHelper.parseTimestamp(s).getTime
+  }
 }
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/GsonFormatter.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/GsonFormatter.scala
index b054554..585447f 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/GsonFormatter.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/GsonFormatter.scala
@@ -28,10 +28,10 @@
       .registerTypeHierarchyAdapter(classOf[Iterable[Any]], new IterableSerializer)
       .registerTypeHierarchyAdapter(classOf[Option[Any]], new OptionSerializer())
 
-  def format[T](values: TraversableOnce[T], out: PrintWriter) {
+  def format[T](values: IterableOnce[T], out: PrintWriter) = {
     val gson: Gson = gsonBuilder.create
 
-    for (value <- values) {
+    values.iterator.foreach {value =>
       gson.toJson(value, out)
       out.println()
     }
@@ -39,7 +39,7 @@
 
   class IterableSerializer extends JsonSerializer[Iterable[Any]] {
     override def serialize(src: Iterable[Any], typeOfSrc: Type, context: JsonSerializationContext): JsonElement = {
-      import scala.collection.JavaConverters._
+      import scala.jdk.CollectionConverters._
       context.serialize(src.asJava)
     }
   }
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/JsonStreamedResultBuilder.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/JsonStreamedResultBuilder.scala
index 004259e..7e3c507 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/JsonStreamedResultBuilder.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/JsonStreamedResultBuilder.scala
@@ -18,8 +18,10 @@
 
 import com.google.gerrit.extensions.restapi.BinaryResult
 
+import scala.util.Using
+
 class GsonStreamedResult[T](val jsonFmt: GsonFormatter,
-                            val committers: TraversableOnce[T]) extends BinaryResult {
+                            val committers: IterableOnce[T]) extends BinaryResult {
   override def writeTo(os: OutputStream) =
-    ManagedResource.use(new PrintWriter(os))(jsonFmt.format(committers, _))
+    Using.resource(new PrintWriter(os))(jsonFmt.format(committers, _))
 }
diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/ManagedResources.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/ManagedResources.scala
deleted file mode 100644
index 5cf2b74..0000000
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/common/ManagedResources.scala
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright (C) 2017 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.googlesource.gerrit.plugins.analytics.common
-
-object ManagedResource {
-  def use[A <: { def close(): Unit }, B](resource: A)(code: A ⇒ B): B =
-    try
-      code(resource)
-    finally
-      resource.close()
-}
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BotLikeExtractorImplSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BotLikeExtractorImplSpec.scala
index 42b0d1c..83e3871 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BotLikeExtractorImplSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BotLikeExtractorImplSpec.scala
@@ -16,9 +16,10 @@
 
 import com.googlesource.gerrit.plugins.analytics.AnalyticsConfig
 import com.googlesource.gerrit.plugins.analytics.test.GerritTestDaemon
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
-class BotLikeExtractorImplSpec extends FlatSpec with Matchers with GerritTestDaemon {
+class BotLikeExtractorImplSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon {
 
   behavior of "isBotLike"
 
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractorSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractorSpec.scala
index 07909ff..d765af3 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractorSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/BranchesExtractorSpec.scala
@@ -2,10 +2,11 @@
 
 import com.google.gerrit.acceptance.UseLocalDisk
 import com.googlesource.gerrit.plugins.analytics.test.GerritTestDaemon
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class BranchesExtractorSpec extends FlatSpec with Matchers with GerritTestDaemon {
+class BranchesExtractorSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon {
   def commitsBranches = new BranchesExtractor(testFileRepository.getRepository)
 
   behavior of "branchesOfCommit"
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/IgnoreFileSuffixFilterSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/IgnoreFileSuffixFilterSpec.scala
index 4ed373c..aefd3c2 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/IgnoreFileSuffixFilterSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/IgnoreFileSuffixFilterSpec.scala
@@ -18,10 +18,11 @@
 import com.googlesource.gerrit.plugins.analytics.AnalyticsConfig
 import com.googlesource.gerrit.plugins.analytics.test.GerritTestDaemon
 import org.eclipse.jgit.treewalk.TreeWalk
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class IgnoreFileSuffixFilterSpec extends FlatSpec with Matchers with GerritTestDaemon {
+class IgnoreFileSuffixFilterSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon {
 
   behavior of "IgnoreFileSuffixFilter"
 
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/UserActivityHistogramSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/UserActivityHistogramSpec.scala
index 7dbe121..2c680e8 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/UserActivityHistogramSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/common/UserActivityHistogramSpec.scala
@@ -17,10 +17,11 @@
 import com.google.gerrit.acceptance.UseLocalDisk
 import com.googlesource.gerrit.plugins.analytics.common.AggregationStrategy.EMAIL_YEAR
 import com.googlesource.gerrit.plugins.analytics.test.GerritTestDaemon
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class UserActivityHistogramSpec extends FlatSpec with Matchers with GerritTestDaemon {
+class UserActivityHistogramSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon {
 
   "UserActivityHistogram" should "return no activities" in {
     val filter = new AggregatedHistogramFilterByDates(aggregationStrategy = EMAIL_YEAR)
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregatedHistogramFilterByDatesSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregatedHistogramFilterByDatesSpec.scala
index 3128b2c..c21d52d 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregatedHistogramFilterByDatesSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregatedHistogramFilterByDatesSpec.scala
@@ -21,10 +21,12 @@
 import com.googlesource.gerrit.plugins.analytics.common.{AggregatedHistogramFilterByDates, BranchesExtractor}
 import org.eclipse.jgit.lib.PersonIdent
 import org.gitective.core.CommitFinder
-import org.scalatest.{BeforeAndAfterEach, FlatSpec, Matchers}
+import org.scalatest.BeforeAndAfterEach
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class AggregatedHistogramFilterByDatesSpec extends FlatSpec with GerritTestDaemon with BeforeAndAfterEach with Matchers {
+class AggregatedHistogramFilterByDatesSpec extends AnyFlatSpecLike with GerritTestDaemon with BeforeAndAfterEach with Matchers {
 
   "Author history filter" should
     "select one commit without intervals restriction" in {
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregationSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregationSpec.scala
index c3d2087..063045b 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregationSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/AggregationSpec.scala
@@ -15,19 +15,20 @@
 package com.googlesource.gerrit.plugins.analytics.test
 
 import java.util.Date
-
 import com.google.gerrit.acceptance.UseLocalDisk
 import com.googlesource.gerrit.plugins.analytics.common.AggregationStrategy._
-import com.googlesource.gerrit.plugins.analytics.common.DateConversions.isoStringToLongDate
+import com.googlesource.gerrit.plugins.analytics.common.DateConversions.StringOps
 import com.googlesource.gerrit.plugins.analytics.common.TestUtils
 import org.eclipse.jgit.revwalk.RevCommit
-import org.scalatest.{FlatSpec, Inspectors, Matchers}
+import org.scalatest.Inspectors
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class AggregationSpec extends FlatSpec with Matchers with GerritTestDaemon with TestUtils with Inspectors {
+class AggregationSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon with TestUtils with Inspectors {
 
   def commitAtDate(committer: String, when: String, content: String): RevCommit = {
-    val personIdent = newPersonIdent(committer, committer, new Date(isoStringToLongDate(when)))
+    val personIdent = newPersonIdent(committer, committer, new Date(when.isoStringToLongDate))
     testFileRepository.commitFile("somefile", content, committer = personIdent, author = personIdent)
   }
 
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitInfoSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitInfoSpec.scala
index 4873328..178de2f 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitInfoSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitInfoSpec.scala
@@ -2,12 +2,13 @@
 
 import com.googlesource.gerrit.plugins.analytics.CommitInfo
 import com.googlesource.gerrit.plugins.analytics.common.GsonFormatter
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
-class CommitInfoSpec extends FlatSpec with Matchers {
+class CommitInfoSpec extends AnyFlatSpecLike with Matchers {
 
   "CommitInfo" should "be serialised as JSON correctly" in {
-    val commitInfo = CommitInfo(sha1 = "sha", date = 1000l, merge = false, botLike = false, files = Set("file1", "file2"))
+    val commitInfo = CommitInfo(sha1 = "sha", date = 1000L, merge = false, botLike = false, files = Set("file1", "file2"))
 
     val gsonBuilder = new GsonFormatter().gsonBuilder
 
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsCommentLinkSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsCommentLinkSpec.scala
index c02cb0c..28c5ebe 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsCommentLinkSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsCommentLinkSpec.scala
@@ -20,18 +20,20 @@
 import com.googlesource.gerrit.plugins.analytics.IssueInfo
 import com.googlesource.gerrit.plugins.analytics.common.{CommitsStatistics, Statistics}
 import org.eclipse.jgit.lib.Repository
-import org.scalatest.{FlatSpec, Inside, Matchers}
+import org.scalatest.Inside
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 @UseLocalDisk
-class CommitStatisticsCommentLinkSpec extends FlatSpec with GerritTestDaemon with TestCommitStatisticsNoCache with Matchers with Inside {
+class CommitStatisticsCommentLinkSpec extends AnyFlatSpecLike with GerritTestDaemon with TestCommitStatisticsNoCache with Matchers with Inside {
 
   def createCommentLinkInfo(pattern: String, link: Option[String] = None, html: Option[String] = None) = {
     val info = new CommentLinkInfo
     info.`match` = pattern
-    info.link = link.getOrElse(null)
-    info.html = html.getOrElse(null)
+    info.link = link.orNull
+    info.html = html.orNull
     info
   }
 
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsSpec.scala
index cb000e6..e78c1d9 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/CommitStatisticsSpec.scala
@@ -18,10 +18,12 @@
 import com.google.gerrit.entities.Project
 import com.googlesource.gerrit.plugins.analytics.CommitInfo
 import com.googlesource.gerrit.plugins.analytics.common.{CommitsStatistics, Statistics}
-import org.scalatest.{FlatSpec, Inside, Matchers}
+import org.scalatest.Inside
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class CommitStatisticsSpec extends FlatSpec with GerritTestDaemon with TestCommitStatisticsNoCache with Matchers with Inside {
+class CommitStatisticsSpec extends AnyFlatSpecLike with GerritTestDaemon with TestCommitStatisticsNoCache with Matchers with Inside {
   class TestEnvironment {
     val repo = fileRepository
     val stats = new Statistics(fileRepositoryName, commitsStatisticsNoCache)
@@ -38,10 +40,10 @@
   }
 
   it should "sum to another compatible CommitStatistics generating an aggregated stat" in {
-    val commit1 = CommitInfo("sha_1", 1000l, false, botLike = false, Set("file1"))
-    val commit2 = CommitInfo("sha_2", 2000l, false, botLike = false, Set("file1"))
-    val commit3 = CommitInfo("sha_3", 3000l, false, botLike = false, Set("file2"))
-    val commit4 = CommitInfo("sha_4", 1000l, false, botLike = false, Set("file1"))
+    val commit1 = CommitInfo("sha_1", 1000L, false, botLike = false, Set("file1"))
+    val commit2 = CommitInfo("sha_2", 2000L, false, botLike = false, Set("file1"))
+    val commit3 = CommitInfo("sha_3", 3000L, false, botLike = false, Set("file2"))
+    val commit4 = CommitInfo("sha_4", 1000L, false, botLike = false, Set("file1"))
 
     val stat1 = CommitsStatistics(3, 4, false, false, List(commit1, commit2))
     val stat2 = CommitsStatistics(5, 7, false, false, List(commit3, commit4))
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/ContributorsServiceSpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/ContributorsServiceSpec.scala
index acefed1..a5d5558 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/ContributorsServiceSpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/ContributorsServiceSpec.scala
@@ -22,12 +22,14 @@
 import com.googlesource.gerrit.plugins.analytics.common.AggregationStrategy.EMAIL_HOUR
 import com.googlesource.gerrit.plugins.analytics.common.GsonFormatter
 import com.googlesource.gerrit.plugins.analytics.test.TestAnalyticsConfig.IGNORED_FILE_SUFFIX
-import org.scalatest.{FlatSpec, Inside, Matchers}
+import org.scalatest.Inside
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 @UseLocalDisk
-class ContributorsServiceSpec extends FlatSpec with Matchers with GerritTestDaemon with Inside {
+class ContributorsServiceSpec extends AnyFlatSpecLike with Matchers with GerritTestDaemon with Inside {
 
   "ContributorsService" should "get commit statistics" in {
     val aContributorName = "Contributor Name"
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/GerritTestDaemon.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/GerritTestDaemon.scala
index 2feb82d..abb155e 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/GerritTestDaemon.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/GerritTestDaemon.scala
@@ -71,7 +71,7 @@
   def newPersonIdent(name: String = "Test Person", email: String = "person@test.com", ts: Date = new Date()) =
     new PersonIdent(new PersonIdent(name, email), ts)
 
-  override def beforeEach {
+  override def beforeEach() = {
     daemonTest.setUpTestPlugin()
     fileRepositoryName = daemonTest.newProject(testSpecificRepositoryName)
     fileRepository = daemonTest.getRepository(fileRepositoryName)
diff --git a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/UserActivitySummarySpec.scala b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/UserActivitySummarySpec.scala
index a5a5e10..3e2289e 100644
--- a/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/UserActivitySummarySpec.scala
+++ b/src/test/scala/com/googlesource/gerrit/plugins/analytics/test/UserActivitySummarySpec.scala
@@ -6,10 +6,11 @@
 import com.googlesource.gerrit.plugins.analytics.common.AggregationStrategy.EMAIL
 import com.googlesource.gerrit.plugins.analytics.common.{Statistics, TestUtils}
 import org.eclipse.jgit.lib.Repository
-import org.scalatest.{FlatSpec, Matchers}
+import org.scalatest.flatspec.AnyFlatSpecLike
+import org.scalatest.matchers.should.Matchers
 
 @UseLocalDisk
-class UserActivitySummarySpec extends FlatSpec with GerritTestDaemon with TestCommitStatisticsNoCache with TestUtils with Matchers {
+class UserActivitySummarySpec extends AnyFlatSpecLike with GerritTestDaemon with TestCommitStatisticsNoCache with TestUtils with Matchers {
 
   "numCommits" should "count only comments filtered by their merge status" in {
     val personEmail = "aCommitter@aCompany.com"