Do not run Sonar analysis on PR

Author: jaaufauvre

.travis.yml

@@ -5,7 +5,8 @@ matrix:
   fast_finish: true
   include:
   - jdk: oraclejdk8
-    env: WITH_SONAR_ANALYSIS=true
+    # Do not run analysis on PR (secure env variables like SONAR_TOKEN are not always available)
+    env: WITH_SONAR_ANALYSIS=$([ "$TRAVIS_PULL_REQUEST" = "false" ] && echo true || echo false)
   - jdk: oraclejdk9
   - jdk: openjdk8
   - jdk: openjdk9