docs: private JsonNode invokeCallbackSet(final SetRequest req) {
          final Object obj = this.getObject(req.getObjref());
          String setterMethodName = javaScriptPropertyToJavaPropertyName("set", req.getProperty());
  
          Method setter = null;
          for (Method method: obj.getClass().getMethods()) {
              if (method.getName().equals(setterMethodName)) {
                  setter = method;
                  break;
              }
          }
  
          if (setter == null) {
              throw new JsiiException("Unable to find property setter " + setterMethodName);
          }
  
          final Object arg = JsiiObjectMapper.treeToValue(req.getValue(), setter.getParameterTypes()[0]);
          return JsiiObjectMapper.valueToTree(invokeMethod(obj, setter, arg));
      }