We are using a custom checkstyle configuration file which is based on google's one, is advisable to use one of the google style configuration files in IDEs to reduce the friction with checkstyle and automate styling.
To build the plugin and run all tests just run mvn clean verify
To use the plugin, install it (by copying the jar from target folder) in lib/ext/ folder of the JMeter installation.
Run JMeter and check the new Siebel HTTP(S) Test Script Recorder is available.