Make mvn site optional since not working yet with jdk9

Author: laurentgo

.travis.yml

@@ -86,6 +86,7 @@ matrix:
     - $TRAVIS_BUILD_DIR/ci/travis_script_java.sh
   - language: java
     os: linux
+    env: ARROW_TRAVIS_SKIP_SITE=yes
     jdk: oraclejdk9
     script:
     - $TRAVIS_BUILD_DIR/ci/travis_script_java.sh

ci/travis_script_java.sh

@@ -24,8 +24,7 @@ JAVA_DIR=${TRAVIS_BUILD_DIR}/java
 pushd $JAVA_DIR
 
 export MAVEN_OPTS="$MAVEN_OPTS -Dorg.slf4j.simpleLogger.defaultLogLevel=warn"
-mvn -B test
 mvn -B install
-mvn -B site
+[ "${ARROW_TRAVIS_SKIP_SITE}" = "yes" ] || mvn -B site
 
 popd