test.cs

// Serialize the XRechnung object to JSON
string json = JsonSerializer.Serialize(xRechnung);

// Generate the ZUGFeRD XML
string xmlZugferd = xRechnung.CreateXML();

// Load metadata from the XML file
string metaData = File.ReadAllText("metadata.xml");

// Create an embedded file for the ZUGFeRD invoice
var zugferdInvoice = new TXTextControl.EmbeddedFile(
    "factur-x.xml",
    Encoding.UTF8.GetBytes(xmlZugferd),
    metaData)
{
    Description = "factur-x",
    Relationship = "Alternative",
    MIMEType = "application/xml",
    LastModificationDate = DateTime.Now
};

// Configure save settings with the embedded file
var saveSettings = new TXTextControl.SaveSettings
{
    EmbeddedFiles = new[] { zugferdInvoice }
};

// Create, modify, and save the PDF document
using (var tx = new TXTextControl.ServerTextControl())
{
    tx.Create();
    tx.Text = "Test Document";
    tx.Save("test.pdf", TXTextControl.StreamType.AdobePDFA, saveSettings);
}