JDK9 Travis job and early migration

.travis.yml

@@ -1,15 +1,13 @@
 language: java
 sudo: false
 
-jdk:
-  - oraclejdk8
-
-env:
- - TERM=dumb
-
 before_install:
+ - if [[ "x$JDK" == *'x9'* ]]; then remove_dir_from_path $JAVA_HOME/bin; export JAVA_HOME=/usr/lib/jvm/java-9-oracle; export PATH=$JAVA_HOME/bin:$PATH; java -Xmx32m -version; fi
  - cp gradle.properties.ci gradle.properties
 
+install:
+ - ./gradlew assemble --stacktrace
+
 script:
  - JAVA_OPTS="-Xmx384m -XX:+UseG1GC -XX:SoftRefLRUPolicyMSPerMB=0 -noverify" ./gradlew check
  - sh -c 'cd examples/write-behind-rxjava && mvn test'
@@ -19,12 +17,26 @@ after_success:
 
 matrix:
   fast_finish: true
-
-addons:
-  apt:
-    packages:
-      - oracle-java8-installer
-
+  include:
+    - jdk: oraclejdk8 # this will be overwritten by before_install above
+      addons:
+        apt:
+          packages:
+            - oracle-java9-installer
+      env:
+        JDK=9
+        TERM=dumb
+# Temporary disable JDK8
+#    - jdk: oraclejdk8
+#      env:
+#        TERM=dumb
+
+# https://docs.travis-ci.com/user/languages/java/#Projects-Using-Gradle
+
+before_cache:
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
 cache:
   directories:
-    - $HOME/.gradle
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/

build.gradle

@@ -34,7 +34,10 @@ allprojects {
 subprojects {
   apply plugin: 'com.github.ethankhall.semantic-versioning'
   apply plugin: 'nebula.provided-base'
-  apply plugin: 'net.ltgt.errorprone'
+  if (!JavaVersion.current().isJava9Compatible()) {
+    // TODO: figure out which errorprone version supports JDK 9+
+    apply plugin: 'net.ltgt.errorprone'
+  }
   apply plugin: 'java'
   apply plugin: 'osgi'
 

gradle/dependencies.gradle

@@ -25,7 +25,7 @@
  */
 ext {
   versions = [
-    akka: '2.3.15',
+    akka: '2.4.9-RC2',
     commons_compress: '1.12',
     commons_lang3: '3.4',
     config: '1.3.0',
@@ -81,7 +81,7 @@ ext {
   ]
 
   libraries = [
-    akka: "com.typesafe.akka:akka-actor_2.10:${versions.akka}",
+    akka: "com.typesafe.akka:akka-actor_2.11:${versions.akka}",
     commons_compress: "org.apache.commons:commons-compress:${versions.commons_compress}",
     commons_lang3: "org.apache.commons:commons-lang3:${versions.commons_lang3}",
     config: "com.typesafe:config:${versions.config}",

simulator/build.gradle

@@ -32,6 +32,10 @@ test {
 
 tasks.withType(Javadoc) {
   options.addStringOption('Xdoclint:none', '-quiet')
+  if (!JavaVersion.current().isJava9Compatible()) {
+    // https://github.com/akka/akka/issues/21165
+    enabled = false
+  }
 }
 
 run {