Test.cs

using System;
using System.IO;
using System.Collections.Generic;

public interface IWriterService
{
    Stream WriteTXT<T>(List<T> content, string delimator, string header = "", bool isHeader = false) where T : class;
}

public class WriterService : IWriterService
{
    public WriterService()
    {}

    public Stream WriteTXT<T>(List<T> content, string delimator, string header, bool isHeader = false) where T : class
    {
        var stream = new MemoryStream();
        TextWriter writer = new StreamWriter(stream);
        if (isHeader)
            writer.Write(header);
        foreach (var item in content)
        {
            writer.Write(item);
            writer.Write(delimator);
        }
        writer.Flush();
        stream.Position = 0;
        return stream;
    }
}

class PartDetailInformation {}
class ApiConstants
{
    public static string KroneFileDelimiter => "";
    public static string PartLocatorFileHeader => "";
}

class Test
{
    static void Main()
    {
        var _writerService = new WriterService();
        List<PartDetailInformation> partLocatorFiltered = new List<PartDetailInformation>();
        using var stream = _writerService.WriteTXT(partLocatorFiltered, ApiConstants.KroneFileDelimiter, ApiConstants.PartLocatorFileHeader,true);
    }
}