The ClientBehaviorContext.Parameter is not available from requestParameterMap

public String onclick(UIComponent component, FacesContext context) {
  Collection<ClientBehaviorContext.Parameter> paramList = new ArrayList<>();
  paramList.add(new javax.faces.component.behavior.ClientBehaviorContext.Parameter("my_param", "my_value"));
  Map<String, List<ClientBehavior>> behaviors = ((ClientBehaviorHolder) component).getClientBehaviors();
  String onclick = ClientBehaviorRendererUtils.buildBehaviorChain(context, component, component.getClientId(), ClientBehaviorEvents.CLICK, paramList, ClientBehaviorEvents.ACTION, paramList, behaviors, null , null);
  return onclick;
}

Map<String,String> paramMap = facesContext.getExternalContext().getRequestParameterMap();
// this works in 2.2.8
String myParamValue = paramMap.get("my_param"); // null

// in 2.3-next parameters are wrapped in params
String paramValue = paramMap.get("params"); // [object Object]

params: {
  my_param: my_value
}