/**
* @param ugi A user group information.
* @return true if delegation token operation is allowed
*/
private boolean isAllowedDelegationTokenOp(UserGroupInformation ugi) throws IOException {
AuthenticationMethod authMethod = ugi.getAuthenticationMethod();
if (authMethod == AuthenticationMethod.PROXY) {
authMethod = ugi.getRealUser().getAuthenticationMethod();
}
if (authMethod != AuthenticationMethod.KERBEROS
&& authMethod != AuthenticationMethod.KERBEROS_SSL