Как загрузить вложение с помощью SO_DOCUMENT_READ_API1?

Наконец нашел решение: [...]

SO_DOCUMENT_READ_API1Response responseAttachment = new SO_DOCUMENT_READ_API1Response();
responseAttachment = RFCClient.SO_DOCUMENT_READ_API1(requestAttachment);

    SOLIX[] BinaryLines = responseAttachment.CONTENTS_HEX;
    ulong file_size;
    ulong.TryParse(responseAttachment.DOCUMENT_DATA.DOC_SIZE, out file_size);
    String FolderPath = DestinationPath;
    
    String path = FolderPath + "\\" + responseAttachment.DOCUMENT_DATA.OBJ_DESCR + "." + responseAttachment.DOCUMENT_DATA.OBJ_TYPE;
    FileStream fis = new FileStream(path, FileMode.Create);

    foreach (SOLIX Item in BinaryLines)
    {
        Byte[] bytes = Item.LINE;
        fis.Write(bytes, 0, bytes.Length);
        int rest = 255 - bytes.Length;

        if (rest < 1) continue;
    
        for (int i = 1; i<= rest; i++)
        {
            if ((ulong) fis.Length >= file_size)
                break;
            fis.WriteByte(0);

        }
    }
    fis.Close();