/**
  * Creates a manager allowing the management of a Couchbase cluster.
  *
  * @param $username The administration username.
  * @param $password The administration password.
  * @return CouchbaseClusterManager
  */
 public function manager($username, $password)
 {
     if (!$this->_manager) {
         $this->_manager = new CouchbaseClusterManager(cbdsn_stringify($this->_dsn), $username, $password);
     }
     return $this->_manager;
 }
 /**
  * Creates a manager allowing the management of a Couchbase cluster.
  *
  * @param $username The administration username.
  * @param $password The administration password.
  * @return CouchbaseClusterManager
  */
 public function manager($username = '', $password = '')
 {
     if (!$this->_manager) {
         if (!($username && $password) && $this->authenticator) {
             $credentials = $this->authenticator->getCredentials('cluster-mgmt');
             $username = $credentials[0];
             $password = $credentials[1];
         }
         if (!($username && $password)) {
             throw new InvalidArgumentException('invalid credentials for cluster manager');
         }
         $this->_manager = new CouchbaseClusterManager(cbdsn_stringify($this->_dsn), $username, $password);
     }
     return $this->_manager;
 }