public ArtifactCollection Specification(string buildSpecification)
        {
            var xml = _caller.GetRaw(string.Format("/repository/download/{0}/{1}/teamcity-ivy.xml", _buildConfigId, buildSpecification));

            var document = new XmlDocument();

            document.LoadXml(xml);
            var artifactNodes = document.SelectNodes("//artifact");

            if (artifactNodes == null)
            {
                return(null);
            }
            var list = new List <string>();

            foreach (XmlNode node in artifactNodes)
            {
                var nameNode      = node.SelectSingleNode("@name");
                var extensionNode = node.SelectSingleNode("@ext");
                var artifact      = string.Empty;
                if (nameNode != null)
                {
                    artifact = nameNode.Value;
                }
                if (extensionNode != null)
                {
                    artifact += "." + extensionNode.Value;
                }
                list.Add(string.Format("/repository/download/{0}/{1}/{2}", _buildConfigId, buildSpecification, artifact));
            }
            return(new ArtifactCollection(_caller, list));
        }