Merge remote-tracking branch 'origin/master'

Author: lvyahui8

.travis.yml

@@ -4,4 +4,7 @@ jdk:
 sudo: false
 script: "mvn cobertura:cobertura"
 after_success:
- - bash <(curl -s https://codecov.io/bash)
+ - bash <(curl -s https://codecov.io/bash)
+cache:
+ directories:
+ - $HOME/.m2