public Task<List<Contract>> GetContractsAsync()
{
string uri = string.Format("{0}/{1}/contracts?api-version=1.6", graphApiUrl, tenant_name);
APIService service = new APIService(uri);
service.Request.Headers.Add("Authorization", "Bearer " + oauth_token.access_token);
dynamic result = service.GetAsync<dynamic>();
return result.value.ToObject<List<Contract>>();
}