add global sonar exclusion for rule s6212

pom.xml

@@ -123,6 +123,10 @@
     <plugin.versions-maven.version>2.14.2</plugin.versions-maven.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+    <!-- The following properties are used to ignore certain SonarQube rules. -->
+    <sonar.issue.ignore.multicriteria>e1</sonar.issue.ignore.multicriteria>
+    <sonar.issue.ignore.multicriteria.e1.resourceKey>**/*.java</sonar.issue.ignore.multicriteria.e1.resourceKey>
+    <sonar.issue.ignore.multicriteria.e1.ruleKey>java:S6212</sonar.issue.ignore.multicriteria.e1.ruleKey>
     <!-- With Java 8 and the latest version of surefire, user.timezone is not read correctly.  Reevaluate one day.
          See https://issues.apache.org/jira/browse/SUREFIRE-1176 or
          http://stackoverflow.com/questions/19121928/java-system-getproperty-user-timezone-does-not-work