code: public static ntp_param[] get_filtered(nitro_service service, String filter) throws Exception
  	{
  		ntp_param obj = new ntp_param();
  		options option = new options();
  		option.set_filter(filter);
  		ntp_param[] response = (ntp_param[]) obj.getfiltered(service, option);
  		return response;
  	}
docs: Use this API to fetch filtered set of ntp_param resources.
  filter string should be in JSON format.eg: "vm_state:DOWN,name:[a-z]+"