public function checkRestrictedGrantType($client_id, $grant_type)
	{
		// get client details
		$client = $this->getClientDetails($client_id);

		// check to make sure grant type is acceptable for client
		if (isset($client['grant_types']))
		{
			$grant_types = explode(' ', $client['grant_types']);
			return in_array($grant_type, (array) $grant_types);
		}

		return true;
	}