async public void Parse()
        {
            CancellationToken token = new CancellationToken();
            var path = @"C:\repos\ConsoleApp7\ConsoleApp7\bin\test2.xml";

            var xmlTextReader = new XmlTextReader(path);
            var data = await XDocument.LoadAsync(xmlTextReader, LoadOptions.PreserveWhitespace, token);
        }

S> async public void Parse()
S>        {
S>            CancellationToken token = new CancellationToken();
S>            var path = @"C:\repos\ConsoleApp7\ConsoleApp7\bin\test2.xml";

S>            var xmlTextReader = new XmlTextReader(path);
S>            var data = await XDocument.LoadAsync(xmlTextReader, LoadOptions.PreserveWhitespace, token);
S>        }
S>

 var xmlTextReader = XmlReader.Create(path, new XmlReaderSettings { Async = true });

public async Task Parse()
{
    CancellationToken token = new CancellationToken();
    var path = @"C:\repos\ConsoleApp7\ConsoleApp7\bin\test2.xml";

    using (var xmlTextReader = XmlReader.Create(path, new XmlReaderSettings { Async = true }))
    {
        var data = await XDocument.LoadAsync(xmlTextReader, LoadOptions.PreserveWhitespace, token);
    }
}

System.NotImplementedException
  HResult=0x80004001
  Message=The method or operation is not implemented.
  Source=System.Private.Xml
  StackTrace:
   at System.Xml.XmlReader.ReadAsync()
   at System.Xml.Linq.XDocument.<LoadAsyncInternal>d__25.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at TestLoadAsync.Program.<Main>d__0.MoveNext() in C:\Users\sdanyliv\source\repos\TestLoadAsync\TestLoadAsync\Program.cs:line 22
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at TestLoadAsync.Program.<Main>(String[] args)