use openjdk 8 for travis builds

Author: Ashish

.travis.yml

@@ -13,7 +13,7 @@ script:
   - if ([ "$TRAVIS_BRANCH" == "master" ] && [ "$TRAVIS_PULL_REQUEST" == "false" ]) || [ -n "$TRAVIS_TAG" ]; then .travis/deploy.sh; else ./mvnw clean compile scoverage:report; fi
 
 
-jdk: oraclejdk8
+jdk: openjdk8
 
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