fix travis build

Artem Labazin · Artem Labazin · commit 59fdf860414c · 2020-06-12T01:58:02.000+03:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,8 +1,10 @@
 
+os: linux
+
 language: java
 
 jdk:
-  - oraclejdk8
+  - openjdk8
 
 services:
   - docker
