question: public void start ( ) { if ( reportRunner == null ) { throw new IllegalStateException ( "Programmatic error, the reportRunner is still NULL when 'start' was called." ) ; } scheduledExecutorService . scheduleAtFixedRate ( reportRunner , period , period , TimeUnit . MILLISECONDS ) ; }
target:  Begins the associated reporting service provided by the given implementation.  In most implementations, no action will occur until this method is invoked. The implementing class must have set 'reportRunner' prior to this method being called.