private static ClientContext CreateAcsClientContextForUrl(SPRemoteEventProperties properties, Uri sharepointUrl)
{
string contextTokenString = properties.ContextToken;
if (String.IsNullOrEmpty(contextTokenString))
{
return null;
}
SharePointContextToken contextToken = ReadAndValidateContextToken(contextTokenString, OperationContext.Current.IncomingMessageHeaders.To.Host);
string accessToken = GetAccessToken(contextToken, sharepointUrl.Authority).AccessToken;
return GetClientContextWithAccessToken(sharepointUrl.ToString(), accessToken);
}