Use trusty dist only for Oracle JDK8 and add Open JDK 13 build

Author: filiphr

.travis.yml

@@ -1,16 +1,17 @@
 language: java
 
 sudo: false
-dist: trusty
 
 install: true
 
 matrix:
   include:
   - jdk: openjdk8
   - jdk: oraclejdk8
+    dist: trusty
   - jdk: openjdk11
   - jdk: openjdk12
+  - jdk: openjdk13
   - jdk: openjdk-ea
   allow_failures:
   - jdk: openjdk-ea