docs: public static String optimizerPlanAsJSON(Plan plan) throws Exception {
  		final int parallelism = plan.getDefaultParallelism() == ExecutionConfig.PARALLELISM_DEFAULT ? 1 : plan.getDefaultParallelism();
  
  		Optimizer pc = new Optimizer(new DataStatistics(), new Configuration());
  		pc.setDefaultParallelism(parallelism);
  		OptimizedPlan op = pc.compile(plan);
  
  		return new PlanJSONDumpGenerator().getOptimizerPlanAsJSON(op);
  	}