Cannot convert type 'Newtonsoft.Json.Linq.JProperty' to 'System.Collections.Generic.KeyValuePair'

I'm facing following runtime error

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException
  HResult=0x80131500
  Message=Cannot convert type 'Newtonsoft.Json.Linq.JProperty' to 'System.Collections.Generic.KeyValuePair<string,Newtonsoft.Json.Linq.JToken>'
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>

I'm trying following code:

using Newtonsoft.Json.Linq;
using System.Collections.Generic;
using System.Linq;
using System.Text;

// Function to convert JSON string to C# class as a string
public static string ConvertJsonToCSharpClass(string jsonString)
{
    // Parse the JSON string into a dynamic JObject
    dynamic json = JObject.Parse(jsonString);

    // Generate the C# code for the class using StringBuilder
    var stringBuilder = new StringBuilder();
    stringBuilder.AppendLine("public class RootObject");
    stringBuilder.AppendLine("{");

    // Loop through all the properties in the JObject and generate a property for each one
    foreach (KeyValuePair<string, JToken> property in json)
    {
        string propertyName = property.Key;
        JTokenType propertyType = property.Value.Type;
        string propertyTypeName = GetCSharpTypeName(propertyType);

        stringBuilder.AppendLine($"    public {propertyTypeName} {propertyName} {{ get; set; }}");
    }

    stringBuilder.AppendLine("}");

    // Return the C# class as a string
    return stringBuilder.ToString();
}

// Helper function to get the C# type name from a JTokenType
private static string GetCSharpTypeName(JTokenType type)
{
    switch (type)
    {
        case JTokenType.Boolean:
            return "bool";
        case JTokenType.Integer:
            return "int";
        case JTokenType.Float:
            return "float";
        case JTokenType.String:
            return "string";
        case JTokenType.Date:
            return "DateTime";
        case JTokenType.Array:
            return "List<object>";
        case JTokenType.Object:
            return "object";
        default:
            return "object";
    }
}