code: public String render(String content, RenderContext context) {
      init();
      FilterContext filterContext = new BaseFilterContext();
      filterContext.setRenderContext(context);
      return fp.filter(content, filterContext);
    }
docs: Render an input with text markup and return a String with
  e.g. HTML
  
  @param content String with the input to render
  @param context Special context for the filter engine, e.g. with
  configuration information
  @return result Output with rendered content