Merge pull request #211 from google/travis.java.issues

Fix unreliable Travis builds

Author: j-baker

.travis.yml

@@ -1,11 +1,14 @@
 # sudo/dist/group must be required/trusty/edge to access oraclejdk9 (2016-11-14)
 sudo: required
 dist: trusty
-group: edge
 
 language: java
-jdk:
-  - oraclejdk8
+
+addons:
+  apt:
+    packages:
+      - oracle-java8-installer
+      - oracle-java9-installer
 
 install: ./gradlew clean jar
 script: ./gradlew check