fix v3 travis compiling error (#20002)

minggo · web-flow · commit ec4ebb6ab34f · 2019-08-01T16:33:43.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -105,6 +105,9 @@ script:
 before_install:
 - tools/travis-scripts/before-install.sh
 
+jdk:
+  - oraclejdk8
+
 cache:
   bundler: true
 
