title: How I can specify the version of JDK for travis CI
body: <p>I have the file <code>.travis.yml</code> generated by JHipster and I would like to use adopt open jdk 12 for travis, but I can not set it.</p>
  
  <pre><code>os:
    - linux
  services:
    - docker
  language: java
  matrix:
    include:
      - env:
          - TRAVIS_JDK=adopt@1.12
          - NODE_VERSION=12.13.1
  cache:
    directories:
      - node
      - node_modules
      - $HOME/.m2
  env:
    global:
      - SPRING_OUTPUT_ANSI_ENABLED=ALWAYS
      - SPRING_JPA_SHOW_SQL=false
      - JHI_DISABLE_WEBPACK_LOGS=true
      - NG_CLI_ANALYTICS="false"
      - MAVEN_USER_HOME=$HOME/.m2/repository/
  script:
    - chmod +x mvnw
    - java -version
    - ./mvnw -ntp checkstyle:check
    - ./mvnw -ntp clean verify
    - ./mvnw -ntp verify -Pprod -DskipTests
    - ./mvnw -ntp com.heroku.sdk:heroku-maven-plugin:2.0.5:deploy -DskipTests -Pprod -Dheroku.buildpacks=heroku/jvm -Dheroku.appName=kacetal-library-stock
  notifications:
    webhooks:
      on_success: change  # options: [always|never|change] default: always
      on_failure: always  # options: [always|never|change] default: always
      on_start: false     # default: false
  </code></pre>
  
  <p>Update alternative doesn't work, I always see error: <code>resetting java alternatives</code> and second error <code>update-alternatives: error: no alternatives for mozilla-javaplugin.so</code></p>
  
  <p>And jdk is always OpenJDK 11 <code>openjdk version "11.0.2" 2019-01-15</code></p>