meta.setFilename(fileName);
meta.setMimeType(mimetype);
req.setAttachmentMetadata(meta);
// add TAS credentials
AuthCredentials cred = new AuthCredentials();
AuthorizedRoles_type0 roles = new AuthorizedRoles_type0();
roles.setRole(ROLES);
cred.setAuthorizedRoles(roles);
cred.setParticipantToken(TOKEN);
req.setAuthCredentials(cred);
// test resulting url
// this will throw an exception if the URL is not valid
URL url = new URL(tas.add(req).getUrl().toString());