Remove obsoleted checkstyle check from our check list - it is causing the following failure :

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:2.8:check (default-cli) on project switchyard-tools-parent: Failed during checkstyle configuration: cannot initialize module TreeWalker - Unable to instantiate DoubleCheckedLocking: Unable to instantiate DoubleCheckedLockingCheck -> [Help 1]