using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

using System.Xml.Linq;

public class Program

{

    public static void Main()

    {

        var xmls = "<?xml version=\"1.0\"?>\n<Event xmlns=\"http://schemas.microsoft.com/win/2004/08/events/event\">\n    <System>\n        <Provider Name=\"LMS\" />\n        <EventID Qualifiers=\"32768\">2125</EventID>\n        <Level>4</Level>\n        <Task>3</Task>\n        <Keywords>0x80000000000000</Keywords>\n        <TimeCreated SystemTime=\"2021-05-30T14:05:07.077547800Z\" />\n        <EventRecordID>89958</EventRecordID>\n        <Channel>Application</Channel>\n        <Computer></Computer>\n        <Security/>\n    </System>\n    <EventData>\n        <Data> </Data>\n    </EventData>\n</Event>\n";

        XDocument doc = XDocument.Parse(xmls);

        Dictionary<string, string > dataDictionary = new Dictionary <string, string >();

        foreach(XElement element in doc.Descendants().Where(p => p.HasElements ==false)) 

        {

            int keyInt = 0;

            string keyName = element.Name.LocalName;

            while (dataDictionary.ContainsKey(keyName))

            {

                keyName = element.Name.LocalName + "_" + keyInt++;

            }

            dataDictionary.Add(keyName, element.Value);

​

            if (element.HasAttributes)

            {

                var lmsAttribute = element.FirstAttribute;

                if (lmsAttribute != null)

                {

                    dataDictionary.Add($"{keyName}_{lmsAttribute.Name.LocalName}", lmsAttribute.Value);

                }

            }

        }

        Console.WriteLine(JsonConvert.SerializeObject(dataDictionary, new JsonSerializerSettings { Formatting = Formatting.Indented }));

    }

}

​