Чтобы получить элементы списка, URI API REST, как показано ниже.
http://sp2010/_vti_bin/ListData.svc/listname
Измените код, как показано ниже.
var siteUrl = "http://www.example.com/";
var listName = "MySharePointList";
var uri = new Uri(siteUrl);
var credential = new NetworkCredential("username", "password", "domain");
var credentialsCache = new CredentialCache { { uri, "NTLM", credential } };
var handler = new HttpClientHandler { Credentials = credentialsCache };
HttpClient client = new HttpClient(handler);
client.BaseAddress = new Uri(uri, "/_vti_bin/ListData.svc");
client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
client.DefaultRequestHeaders.Add("ContentType", "application/json;odata=verbose");
var requestURL = siteUrl + "/_vti_bin/ListData.svc/" + listName;
// Make the list request
var result = client.GetAsync(requestURL).Result;
var items= result.Content.ReadAsStringAsync();