adds jdk 9 to travis ci (#6)

* adds jdk 9 to travis ci

* updates gradle-wrapper.properties

* updates sonarqube plugin to 2.6.2 and sourceCompatibility to 11

* corrects sonarcloud addon

Author: kmindi

.travis.yml

@@ -1,8 +1,9 @@
 language: java
 jdk:
   - oraclejdk8
+  - oraclejdk9
 addons:
-  sonarqube:
+  sonarcloud:
     organization: "kmindi-github" # the key of the org you chose at step #3
 cache:
   directories:

build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id "org.sonarqube" version "2.3"
+    id "org.sonarqube" version "2.6.2"
 }
 
 group 'com.cryptoexamples.java'

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.7-all.zip