in TeamCity.ServiceMessages/Write/Special/Impl/Writer/TeamCityTestWriter.cs [96:101]
public void WriteLink(string linkUri, string name)
{
if (string.IsNullOrEmpty(linkUri)) throw new ArgumentException(nameof(linkUri));
if (string.IsNullOrEmpty(name)) throw new ArgumentException(nameof(name));
PostMessage(new ServiceMessage("testMetadata") {{"testName", _testName}, {"type", "link"}, {"value", linkUri}, {"name", name}});
}