docs: private List<Rule> getStyleRules(final String styleProperty) {
          final List<Rule> styleRules = new ArrayList<>(this.json.size());
  
          for (Iterator<String> iterator = this.json.keys(); iterator.hasNext(); ) {
              String styleKey = iterator.next();
              if (styleKey.equals(JSON_STYLE_PROPERTY) ||
                      styleKey.equals(MapfishStyleParserPlugin.JSON_VERSION)) {
                  continue;
              }
              PJsonObject styleJson = this.json.getJSONObject(styleKey);
              final List<Rule> currentRules = createStyleRule(styleKey, styleJson, styleProperty);
              for (Rule currentRule: currentRules) {
                  if (currentRule != null) {
                      styleRules.add(currentRule);
                  }
              }
          }
  
          return styleRules;
      }