trusty

.travis.yml

+dist: trusty
+
 notifications:
   email:
     recipients:
@@ -7,17 +9,19 @@ notifications:
 
 language: java
 
-jdk:
-  - openjdk11
-  - oraclejdk11
-   - openjdk9
-  - oraclejdk9
-  - openjdk8
-  - oraclejdk8
+matrix:
+  include:
+  # On OSX, run with default JDK only.
+  # - os: osx
+  # On Linux, run with specific JDKs only.
+  - os: linux
+    env: CUSTOM_JDK="oraclejdk8"
 
 before_install:
   - echo 'MAVEN_OPTS="$MAVEN_OPTS -Xmx1024m -XX:MaxPermSize=512m -XX:+BytecodeVerificationLocal"' >> ~/.mavenrc
   - cat ~/.mavenrc
+  - if [ "$TRAVIS_OS_NAME" == "osx" ]; then export JAVA_HOME=$(/usr/libexec/java_home); fi
+  - if [ "$TRAVIS_OS_NAME" == "linux" ]; then jdk_switcher use "$CUSTOM_JDK"; fi
 
 script:
   - travis_retry mvn -B clean apache-rat:check