fixes and tweaks

fixed sudo value should been required instead of true

changed to use trusty distribution to see if inconsistent issue getting better

.travis.yml

@@ -12,7 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-sudo: true
+sudo: required
+dist: trusty
 
 language: java
 jdk: