@Override
public Token<DelegationTokenIdentifier> getDelegationToken(
final String renewer) throws IOException {
final HttpOpParam.Op op = GetOpParam.Op.GETDELEGATIONTOKEN;
final Map<?, ?> m = run(op, null, new RenewerParam(renewer));
final Token<DelegationTokenIdentifier> token = JsonUtil.toDelegationToken(m);
SecurityUtil.setTokenService(token, nnAddr);
return token;
}