Fix travis build

Author: jericks

Diff for: .travis.yml

@@ -1,13 +1,5 @@
+dist: bionic
 language: java
-
-# fix for https://github.com/travis-ci/travis-ci/issues/5227    
-before_install:
-  - cat /etc/hosts # optionally check the content *before*
-  - sudo hostname "$(hostname | cut -c1-63)"
-  - sed -e "s/^\\(127\\.0\\.0\\.1.*\\)/\\1 $(hostname | cut -c1-63)/" /etc/hosts > /tmp/hosts
-  - sudo mv /tmp/hosts /etc/hosts
-  - cat /etc/hosts # optionally check the content *after*
-
-jdk:
-    - openjdk7
-    - oraclejdk8
+jdk: openjdk8
+script:
+  - mvn clean package