Add openjdk15 on .travis.yml because openjdk-ea becomed alias of openjdk16

kazuki43zoo · kazuki43zoo · commit 19b6267eb414 · 2020-06-27T09:41:59.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -2,6 +2,7 @@ language: java
 
 jdk:
   - openjdk-ea
+  - openjdk15
   - openjdk14
   - openjdk11
   - openjdk8
