Dear developer I use getAnnotations().add(anno) to generate annotations, ,but they won't display in my browser. Do you need any other method or is it not supported yet.
Addannotations annoadder = new Addannotations();
PDAnnotationFreeText anno = annoadder.setanno(param);
PDPage page = document.getPage(Integer.parseInt(param[0])-1);
page.getAnnotations().add(anno);
best

