build: replace jabba by proper debian installation

.travis.yml

@@ -11,10 +11,11 @@ git:
 before_install:
   # make comparing to origin/master work
   - git remote set-branches --add origin master && git fetch
-  # using jabba for custom jdk management
-  - curl -sL https://raw.githubusercontent.com/shyiko/jabba/0.11.1/install.sh | bash && . ~/.jabba/jabba.sh
-  - jabba install [email protected]
-  - jabba use "[email protected]"
+  # using official adoptopenjdk installation instructions for debian-based distros from https://adoptopenjdk.net/installation.html#linux-pkg
+  - curl wget -qO - https://adoptopenjdk.jfrog.io/adoptopenjdk/api/gpg/key/public | apt-key add -
+  - add-apt-repository --yes https://adoptopenjdk.jfrog.io/adoptopenjdk/deb/
+  - apt-get -qq update
+  - apt-get install -y adoptopenjdk-8-hotspot
   - java -version
 
 addons: