Try to change java version.

.travis.yml

@@ -52,7 +52,9 @@ install:
 - sudo apt-get install openjdk-8-jdk
 - echo "JAVA_HOME=" $JAVA_HOME
 - echo "PATH=" $PATH
-- ll /usr/java
+- which java
+- ls /usr/local/lib/jvm
+- ls /usr/java
 - sudo pip install --upgrade pip
 - sudo pip install setuptools-rust
 - sudo pip install pyOpenSSL