code: public void start() {
          if(started.compareAndSet(false, true)) {
              logger.info("Opening ServiceTracker to search for {} services...", serviceType.getCanonicalName());
              serviceTracker.open(true);
          } else {
              logger.warn("ServiceTracker already open, searching for {} services.", serviceType.getCanonicalName());
          }
      }
docs: Starts the whiteboard.  This will initiate the search for all matching services.