Xamarin.forms HttpClient使用Odata不工作

我使用以下代码访问SAP Odata Web服务：

     string strUrl = "https://...../HandlingUnitSet?$format=json";

        var credentials = new NetworkCredential("user", "usr123");
        var handler = new HttpClientHandler { Credentials = credentials };
        var client = new System.Net.Http.HttpClient(handler);
        client.DefaultRequestHeaders.Accept.Clear();            
        client.DefaultRequestHeaders.Add("Accept", "application/json");

        var response = await client.GetAsync(strUrl);

        string status = response.StatusCode.ToString();
        string header = response.Headers.ToString();
        string cont = response.Content.ToString();

        string contactsJson = response.Content.ReadAsStringAsync().Result;

             UoUnit ObjUnitList = new UoUnit();
            ObjUnitList = JsonConvert.DeserializeObject<UoUnit>(contactsJson);

string strUrl=”https://...../HandlingUnitSet?$format=json”；
var凭证=新网络凭证（“用户”、“usr123”）；
var handler=newhttpclienthandler{Credentials=Credentials}；
var client=new System.Net.Http.HttpClient（处理程序）；
client.DefaultRequestHeaders.Accept.Clear（）；
client.DefaultRequestHeaders.Add（“Accept”、“application/json”）；
var response=await client.GetAsync（strUrl）；
字符串状态=response.StatusCode.ToString（）；
字符串头=response.Headers.ToString（）；
string cont=response.Content.ToString（）；
字符串contactsJson=response.Content.ReadAsStringAsync（）.Result；
UoUnit对象列表=新的UoUnit（）；
ObjUnitList=JsonConvert.DeserializeObject（contactsJson）；

问题：我收到了下面的错误消息

url应该返回Json数据，但我没有得到它。在反序列化对象的行中遇到此错误

---

解析值时遇到意外字符：只要查看错误，我就会认为您实际获得了XML。。。尽管我不能说为什么，因为您请求JSON的请求是正确的。您是否可以尝试将整个响应作为一个字符串（而不解析“JSON”）来查看您得到的确切内容？检查

contactsJson

中的内容。它可能有一些非JSON XML或HTML来告诉您问题所在。

{Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.
  at Newtonsoft.Json.JsonTextReader.ParseValue () [0x002b3] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonTextReader.Read () [0x0004c] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonReader.ReadAndMoveToContent () [0x00000] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonReader.ReadForType (Newtonsoft.Json.Serialization.JsonContract contract, System.Boolean hasConverter) [0x0004a] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Boolean checkAdditionalContent) [0x000db] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonSerializer.DeserializeInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00054] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonSerializer.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonConvert.DeserializeObject (System.String value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) [0x0002d] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonConvert.DeserializeObject[T] (System.String value, Newtonsoft.Json.JsonSerializerSettings settings) [0x00000] in <d32db49e5e3440729da31845c03ddc3a>:0 
  at Newtonsoft.Json.JsonConvert.DeserializeObject[T] (System.String value) [0x00000] in <d32db49e5e3440729da31845c03ddc3a>:0 
   }