How can I get the TimeSpent on an Issue in Jira via the Jira REST API?

[Jakob Holzinger]

Hey, I want to get the TimeSpent on an Issue from Jira with the API. I read the documentation about it and it shoudld work, but when I convert result to a Object of the type Worklog, every Property has it's default values, but why? Here is my Code:

public async Task<string> GetTimeSpentAsync(string issueKey)
{
var jiraConnection = Jira.CreateRestClient(_jiraSettings.Url, _jiraSettings.UserName,
_jiraSettings.Password, new JiraRestClientSettings() { });
var result = await jiraConnection.RestClient.ExecuteRequestAsync(Method.GET, $"/rest/api/2/issue/{issueKey}/worklog");

var workflow = result.ToObject<Worklog>();

if(workflow != null)
{
return workflow.TimeSpent;
}
throw new NullReferenceException();
}

 Here is a Picture of the Propertys in Debug-Mode: