setHeader("Content-Disposition", disposition);
if (disposition == null) { removeHeader("Content-Disposition"); } else {  String currentHeader = getSingleHeader("Content-Disposition"); if (currentHeader != null) { ContentDisposition content = new ContentDisposition(currentHeader); content.setDisposition(disposition); setHeader("Content-Disposition", content.toString()); } else {  setHeader("Content-Disposition", disposition); } }
    public void setDisposition(String disposition) throws MessagingException {        setHeader("Content-Disposition", disposition);    }