Also removing openjdk7 as it no longer supported properly on Travis either

cbetta · cbetta · commit 58b0fb45c2ce · 2018-05-11T11:01:02.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -2,7 +2,6 @@ language: java
 jdk:
   - oraclejdk8
   - oraclejdk9
-  - openjdk7
   - openjdk8
 branches:
   only:
