Update JDK for CI

Author: acoburn

.travis.yml

@@ -35,19 +35,19 @@ jobs:
         # JDK 8
         - name: "Java 8"
           stage: test
-          jdk: oraclejdk8
+          jdk: openjdk8
           script: ./gradlew check install jacocoRootReport --scan
           after_success: ./gradlew coveralls sonarqube
 
         # JDK 11
         - name: "Java 11"
           stage: test
-          jdk: oraclejdk11
+          jdk: openjdk11
           script: ./gradlew check install
 
         - name: "Publish to Sonatype"
           stage: deploy
-          jdk: oraclejdk8
+          jdk: openjdk8
           env: JOB=sonatype
           if: branch = master AND type = push
           # Only automate the publication of SNAPSHOTS