code: public static Rule createDefaultPolygonRule() {
          PolygonSymbolizer polygonSymbolizer = sf.createPolygonSymbolizer();
          Fill fill = createDefaultFill();
          polygonSymbolizer.setFill(fill);
          polygonSymbolizer.setStroke(createDefaultStroke());
  
          Rule rule = sf.createRule();
          rule.setName("New rule");
          rule.symbolizers().add(polygonSymbolizer);
  
          return rule;
      }
docs: Creates a default {@link Rule} for a polygon.
  
  @return the default rule.