您可以在示例化消息时设置属性：

var messageToSend = new Message(Encoding.UTF8.GetBytes(jsonData))
{
    ContentType = "application/json",
    ContentEncoding = "utf-8"
};

发送消息的完整示例：

async Task SendToIoTHub(OdtcDataEventArgs eventArgs)
{
    var sensorValues = eventArgs.GetSensorValues();
    string jsonData = JsonSerializer.Serialize(sensorValues);
    var messageToSend = new Message(Encoding.UTF8.GetBytes(jsonData))
    {
        ContentType = "application/json",
        ContentEncoding = "utf-8"
    };

    if (_deviceClient != null)
    {
        await _deviceClient.SendEventAsync(messageToSend).ConfigureAwait(false);
    }
}