specify jdk8 in travis

ceki · ceki · commit 9752c892fdf4 · 2019-08-10T11:05:48.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,4 +1,9 @@
 language: java
+
+jdk:
+  - openjdk8
+
 notifications:
   email:
       - notification@qos.ch
+
