How to use ireadonlylist<bluetoothcomport> findall()

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C#

I have this class to enumerate Bluetooth COM ports:

public sealed class BluetoothComPort
{
    public static IReadOnlyList<bluetoothcomport> FindAll()
    {
        List<bluetoothcomport> ports = new List<bluetoothcomport>();

        IntPtr handle = NativeMethods.SetupDiGetClassDevs(ref NativeMethods.GUID_DEVCLASS_PORTS, null, IntPtr.Zero, NativeMethods.DIGCF.PRESENT);
        if (handle != IntPtr.Zero)
        {
            try
            {


                NativeMethods.SP_DEVINFO_DATA dat = new NativeMethods.SP_DEVINFO_DATA();
                dat.cbSize = Marshal.SizeOf(dat);
                uint i = 0;

                while (NativeMethods.SetupDiEnumDeviceInfo(handle, i++, ref dat))
                {
                    string remoteServiceName = string.Empty;
                    StringBuilder sbid = new StringBuilder(256);
                    int size;
                    NativeMethods.SetupDiGetDeviceInstanceId(handle, ref dat, sbid, sbid.Capacity, out size);
                    Debug.WriteLine(sbid);
                    long addr = GetBluetoothAddressFromDevicePath(sbid.ToString());

                    // only valid if an outgoing Bluetooth port
                    if (addr != long.MinValue && addr != 0)
                    {
                        IntPtr hkey = NativeMethods.SetupDiOpenDevRegKey(handle, ref dat, NativeMethods.DICS.GLOBAL, 0, NativeMethods.DIREG.DEV, 1);
                        var key = Microsoft.Win32.RegistryKey.FromHandle(new Microsoft.Win32.SafeHandles.SafeRegistryHandle(hkey, true));
                        object name = key.GetValue("PortName");

                        var pkey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("SYSTEM\\CurrentControlSet\\Services\\BTHPORT\\Parameters\\Devices\\" + addr.ToString("x12"));
                        if (pkey != null)
                        {
                            foreach (string nm in pkey.GetSubKeyNames())
                            {
                                if (nm.StartsWith("ServicesFor"))
                                {
                                    var skey = pkey.OpenSubKey(nm);
                                    string s = sbid.ToString();

                                    //bluetooth service uuid from device id string
                                    int ifirst = s.IndexOf("{");
                                    string uuid = s.Substring(ifirst, s.IndexOf("}") - ifirst + 1);
                                    var ukey = skey.OpenSubKey(uuid);

                                    // instance id from device id string
                                    string iid = s.Substring(s.LastIndexOf("_") + 1);
                                    var instKey = ukey.OpenSubKey(iid);

                                    // registry key contains service name as a byte array
                                    object o = instKey.GetValue("PriLangServiceName");
                                    if (o != null)
                                    {
                                        byte[] chars = o as byte[];
                                        remoteServiceName = Encoding.UTF8.GetString(chars).Trim();
                                    }
                                }
                            }
                        }
                        ports.Add(new BluetoothComPort(sbid.ToString(), addr, name.ToString(), remoteServiceName));
                        key.Dispose();
                    }
                }

            }
            finally
            {
                NativeMethods.SetupDiDestroyDeviceInfoList(handle);
            }
        }

        return ports;
    }

    private string _deviceId;
    private long _bluetoothAddress;
    private string _portName;
    private string _remoteServiceName;

    internal BluetoothComPort(string deviceId, long bluetoothAddress, string portName, string remoteServiceName)
    {
        _deviceId = deviceId;
        _bluetoothAddress = bluetoothAddress;
        _portName = portName;
        _remoteServiceName = remoteServiceName;
    }

    public string DeviceId
    {
        get
        {
            return _deviceId;
        }
    }

    public long BluetoothAddress
    {
        get
        {
            return _bluetoothAddress;
        }
    }

    public string PortName
    {
        get
        {
            return _portName;
        }
    }

    public string RemoteServiceName
    {
        get
        {
            return _remoteServiceName;
        }
    }


    private static long GetBluetoothAddressFromDevicePath(string path)
    {
        if (path.StartsWith("BTHENUM"))
        {
            int start = path.LastIndexOf('&');
            int end = path.LastIndexOf('_');
            string addressString = path.Substring(start + 1, (end - start) - 1);

            // may return zero if it is an incoming port (we're not interested in these)
            return long.Parse(addressString, System.Globalization.NumberStyles.HexNumber);

        }

        // not a bluetooth port
        return long.MinValue;
    }

    private static class NativeMethods
    {
        // The SetupDiGetClassDevs function returns a handle to a device information set that contains requested device information elements for a local machine. 
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        internal static extern IntPtr SetupDiGetClassDevs(
            ref Guid classGuid,
            [MarshalAs(UnmanagedType.LPTStr)] string enumerator,
            IntPtr hwndParent,
            DIGCF flags);

        // The SetupDiEnumDeviceInfo function returns a SP_DEVINFO_DATA structure that specifies a device information element in a device information set. 
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool SetupDiEnumDeviceInfo(
            IntPtr deviceInfoSet,
            uint memberIndex,
            ref SP_DEVINFO_DATA deviceInfoData);

        // The SetupDiDestroyDeviceInfoList function deletes a device information set and frees all associated memory.
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool SetupDiDestroyDeviceInfoList(IntPtr deviceInfoSet);

        // The SetupDiGetDeviceInstanceId function retrieves the device instance ID that is associated with a device information element.
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool SetupDiGetDeviceInstanceId(
           IntPtr deviceInfoSet,
           ref SP_DEVINFO_DATA deviceInfoData,
           System.Text.StringBuilder deviceInstanceId,
           int deviceInstanceIdSize,
           out int requiredSize);

        //static Guid GUID_DEVCLASS_BLUETOOTH = new Guid("{E0CBF06C-CD8B-4647-BB8A-263B43F0F974}");
        internal static Guid GUID_DEVCLASS_PORTS = new Guid("{4d36e978-e325-11ce-bfc1-08002be10318}");

        [DllImport("setupapi.dll", SetLastError = true)]
        internal static extern IntPtr SetupDiOpenDevRegKey(IntPtr DeviceInfoSet, ref SP_DEVINFO_DATA DeviceInfoData,
            DICS Scope, int HwProfile, DIREG KeyType, int samDesired);

        [Flags]
        internal enum DICS
        {
            GLOBAL = 0x00000001,  // make change in all hardware profiles
            CONFIGSPECIFIC = 0x00000002,  // make change in specified profile only
        }

        internal enum DIREG
        {
            DEV = 0x00000001,          // Open/Create/Delete device key
            DRV = 0x00000002,          // Open/Create/Delete driver key
        }

        // changes to follow.
        // SETUPAPI.H
        [Flags()]
        internal enum DIGCF
        {
            PRESENT = 0x00000002, // Return only devices that are currently present in a system.
            ALLCLASSES = 0x00000004, // Return a list of installed devices for all device setup classes or all device interface classes. 
            PROFILE = 0x00000008, // Return only devices that are a part of the current hardware profile.
        }


        [StructLayout(LayoutKind.Sequential)]
        internal struct SP_DEVINFO_DATA
        {
            internal int cbSize; // = (uint)Marshal.SizeOf(typeof(SP_DEVINFO_DATA));
            internal Guid ClassGuid;
            internal uint DevInst;
            internal IntPtr Reserved;
        }
    }

}

Please can you explain me how to use this code to enumerate the Bluetooth COM ports?
Thank you

What I have tried:

I'm not able to use that code.