code: private static TupleGenerator asGenerator( JsonObject json)
      {
      TupleGenerator tupleGenerator = new TupleGenerator();
  
      Optional.ofNullable( json.getJsonNumber( TUPLES_KEY))
        .ifPresent( n -> tupleGenerator.setDefaultTupleSize( n.intValue()));
  
      Optional.ofNullable( json.getJsonNumber( SEED_KEY))
        .ifPresent( n -> tupleGenerator.setRandomSeed( n.longValue()));
  
      // Get any combiners for this generator.
      Optional.ofNullable( json.getJsonArray( COMBINERS_KEY))
        .map( combiners -> combiners.getValuesAs( JsonObject.class).stream())
        .orElse( Stream.empty())
        .forEach( combiner -> tupleGenerator.addCombiner( asCombiner( combiner)));
  
      return tupleGenerator;
      }
docs: Returns the generator represented by the given JSON object.