# all duplicate headers and pick one.
            headers = {}
            headers['content-type'] = 'application/x-www-form-urlencoded'
            headers['authorization'] = urllib3.make_headers(
                basic_auth='%s:%s' % (self.cid, self.csec))['authorization']

            response = self._http.urlopen('POST', self.idp_ep,
                                          body="grant_type=client_credentials",