diff --git a/.travis.yml b/.travis.yml
index 834114411..ccad81d19 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,28 +2,45 @@ language: scala
 
 scala:
   - 2.12.8
+  - 2.13.0
 
-script: sbt -Dfile.encoding=UTF8 -J-XX:ReservedCodeCacheSize=256M
-  ++$TRAVIS_SCALA_VERSION
-  mimaReportBinaryIssues
-  scalafmtCheckAll
-  whitesourceCheckPolicies
-  test
+env:
+  global: ADOPTOPENJDK=11
 
 matrix:
   include:
-  - jdk: openjdk8
-  - jdk: openjdk11
+    - scala: 2.12.8
+      env:
+        - ADOPTOPENJDK=8
+        - secure: 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
+      script: sbt -Dfile.encoding=UTF8 -J-XX:ReservedCodeCacheSize=256M
+        ++$TRAVIS_SCALA_VERSION!
+        mimaReportBinaryIssues
+        scalafmtCheckAll
+        whitesourceCheckPolicies
+        test
 
-env:
-  global:
-    - secure: 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
+before_install:
+  # adding $HOME/.sdkman to cache would create an empty directory, which interferes with the initial installation
+  - "[[ -d $HOME/.sdkman/bin ]] || rm -rf $HOME/.sdkman/"
+  - curl -sL https://get.sdkman.io | bash
+  - echo sdkman_auto_answer=true > "$HOME/.sdkman/etc/config"
+  - source "$HOME/.sdkman/bin/sdkman-init.sh"
 
-cache:
-  directories:
-    - $HOME/.ivy2/cache
-    - $HOME/.sbt
+install:
+  - sdk install java $(sdk list java | grep -o "$ADOPTOPENJDK\.[0-9\.]*hs-adpt" | head -1)
+  - unset JAVA_HOME
+  - java -Xmx32m -version
+  - javac -J-Xmx32m -version
+
+script: sbt -Dfile.encoding=UTF8 -J-XX:ReservedCodeCacheSize=256M ++$TRAVIS_SCALA_VERSION! test
 
 before_cache:
   - find $HOME/.ivy2/cache -name "ivydata-*.properties" -delete
   - find $HOME/.sbt        -name "*.lock"               -delete
+
+cache:
+  directories:
+    - $HOME/.coursier
+    - $HOME/.ivy2/cache
+    - $HOME/.sbt
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/LogOptionFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/LogOptionFormats.scala
index e52700c19..f5e851f68 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/LogOptionFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/LogOptionFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait LogOptionFormats { self: sjsonnew.BasicJsonProtocol =>
 implicit lazy val LogOptionFormat: JsonFormat[sbt.internal.util.LogOption] = new JsonFormat[sbt.internal.util.LogOption] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.LogOption = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.readString(js) match {
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.LogOption = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.readString(__js) match {
         case "Always" => sbt.internal.util.LogOption.Always
         case "Never" => sbt.internal.util.LogOption.Never
         case "Auto" => sbt.internal.util.LogOption.Auto
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressEventFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressEventFormats.scala
index 4d836c02d..6478f743a 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressEventFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressEventFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait ProgressEventFormats { self: sbt.internal.util.codec.ProgressItemFormats with sjsonnew.BasicJsonProtocol =>
 implicit lazy val ProgressEventFormat: JsonFormat[sbt.internal.util.ProgressEvent] = new JsonFormat[sbt.internal.util.ProgressEvent] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.ProgressEvent = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.beginObject(js)
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.ProgressEvent = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.beginObject(__js)
       val level = unbuilder.readField[String]("level")
       val items = unbuilder.readField[Vector[sbt.internal.util.ProgressItem]]("items")
       val lastTaskCount = unbuilder.readField[Option[Int]]("lastTaskCount")
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressItemFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressItemFormats.scala
index 3aac75e91..261ab93d4 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressItemFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/ProgressItemFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait ProgressItemFormats { self: sjsonnew.BasicJsonProtocol =>
 implicit lazy val ProgressItemFormat: JsonFormat[sbt.internal.util.ProgressItem] = new JsonFormat[sbt.internal.util.ProgressItem] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.ProgressItem = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.beginObject(js)
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.ProgressItem = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.beginObject(__js)
       val name = unbuilder.readField[String]("name")
       val elapsedMicros = unbuilder.readField[Long]("elapsedMicros")
       unbuilder.endObject()
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/StringEventFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/StringEventFormats.scala
index 2d142f6ec..8b8ef3fe6 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/StringEventFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/StringEventFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait StringEventFormats { self: sjsonnew.BasicJsonProtocol =>
 implicit lazy val StringEventFormat: JsonFormat[sbt.internal.util.StringEvent] = new JsonFormat[sbt.internal.util.StringEvent] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.StringEvent = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.beginObject(js)
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.StringEvent = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.beginObject(__js)
       val level = unbuilder.readField[String]("level")
       val message = unbuilder.readField[String]("message")
       val channelName = unbuilder.readField[Option[String]]("channelName")
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/SuccessEventFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/SuccessEventFormats.scala
index 19621d7c1..8c556ba4e 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/SuccessEventFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/SuccessEventFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait SuccessEventFormats { self: sjsonnew.BasicJsonProtocol =>
 implicit lazy val SuccessEventFormat: JsonFormat[sbt.internal.util.SuccessEvent] = new JsonFormat[sbt.internal.util.SuccessEvent] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.SuccessEvent = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.beginObject(js)
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.SuccessEvent = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.beginObject(__js)
       val message = unbuilder.readField[String]("message")
       unbuilder.endObject()
       sbt.internal.util.SuccessEvent(message)
diff --git a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/TraceEventFormats.scala b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/TraceEventFormats.scala
index 379196a9b..babad8d58 100644
--- a/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/TraceEventFormats.scala
+++ b/internal/util-logging/src/main/contraband-scala/sbt/internal/util/codec/TraceEventFormats.scala
@@ -7,10 +7,10 @@ package sbt.internal.util.codec
 import _root_.sjsonnew.{ Unbuilder, Builder, JsonFormat, deserializationError }
 trait TraceEventFormats { self: sjsonnew.BasicJsonProtocol =>
 implicit lazy val TraceEventFormat: JsonFormat[sbt.internal.util.TraceEvent] = new JsonFormat[sbt.internal.util.TraceEvent] {
-  override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.TraceEvent = {
-    jsOpt match {
-      case Some(js) =>
-      unbuilder.beginObject(js)
+  override def read[J](__jsOpt: Option[J], unbuilder: Unbuilder[J]): sbt.internal.util.TraceEvent = {
+    __jsOpt match {
+      case Some(__js) =>
+      unbuilder.beginObject(__js)
       val level = unbuilder.readField[String]("level")
       val message = unbuilder.readField[Throwable]("message")
       val channelName = unbuilder.readField[Option[String]]("channelName")
diff --git a/internal/util-relation/src/main/scala/sbt/internal/util/Relation.scala b/internal/util-relation/src/main/scala/sbt/internal/util/Relation.scala
index 6a1abd726..61d5acde2 100644
--- a/internal/util-relation/src/main/scala/sbt/internal/util/Relation.scala
+++ b/internal/util-relation/src/main/scala/sbt/internal/util/Relation.scala
@@ -183,7 +183,7 @@ private final class MRelation[A, B](fwd: Map[A, Set[B]], rev: Map[B, Set[A]])
   }
 
   def groupBy[K](discriminator: ((A, B)) => K): Map[K, Relation[A, B]] =
-    all.groupBy(discriminator) mapValues { Relation.empty[A, B] ++ _ }
+    (all.groupBy(discriminator) mapValues { Relation.empty[A, B] ++ _ }).toMap
 
   def contains(a: A, b: B): Boolean = forward(a)(b)
 
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index 771e7e403..d8d241042 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -4,10 +4,11 @@ import sbt.contraband.ContrabandPlugin.autoImport._
 
 object Dependencies {
   val scala212 = "2.12.8"
+  val scala213 = "2.13.0"
 
   def nightlyVersion: Option[String] = sys.props.get("sbt.build.version")
 
-  private val ioVersion = nightlyVersion.getOrElse("1.3.0-M11")
+  private val ioVersion = nightlyVersion.getOrElse("1.3.0-M12")
   private val sbtIO = "org.scala-sbt" %% "io" % ioVersion
 
   def getSbtModulePath(key: String, name: String) = {
diff --git a/project/build.properties b/project/build.properties
index c59667ce9..c9f29468d 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.0-M3
+sbt.version=1.3.0-RC2
diff --git a/project/plugins.sbt b/project/plugins.sbt
index c6e8c962e..7c0f95696 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -1,5 +1,5 @@
 addSbtPlugin("org.scala-sbt" % "sbt-houserules" % "0.3.9")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.0.0")
-addSbtPlugin("org.scala-sbt" % "sbt-contraband" % "0.4.1")
+addSbtPlugin("org.scala-sbt" % "sbt-contraband" % "0.4.4")
 addSbtPlugin("com.lightbend" % "sbt-whitesource" % "0.1.16")
 addSbtPlugin("com.timushev.sbt" % "sbt-updates" % "0.4.1")