code: public Groundy service(Class<? extends GroundyService> groundyClass) {
      if (groundyClass == GroundyService.class) {
        throw new IllegalStateException(
            "This method is meant to set a different GroundyService implementation. "
                + "You cannot use GroundyService.class, http://i.imgur.com/IR23PAe.png");
      }
      checkAlreadyProcessed();
      mGroundyClass = groundyClass;
      return this;
    }
docs: This allows you to use a different GroundyService implementation.
  
  @param groundyClass a different Groundy service implementation
  @return itself