How to get parameters of a selected Category

Hi guys! I’m trying to develop an addin for Revit. Selected category is in the variable called “category”. Now, how to make a list of parameters that belong to that category and put it inside of a new ComboBox?
Should I create a list of all elements (in Class.cs) inside of that selected category and using foreach get the parameters of every single element (all types of parameters) to later create a collection out of them and finally put it in a new ComboBox?

Class.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.Attributes;
using Autodesk.Revit.UI.Selection;

namespace CombineParameters
{
    [Transaction(TransactionMode.Manual)]
    [RegenerationAttribute(RegenerationOption.Manual)]

    public class Class : IExternalCommand
    {

        public Result Execute(ExternalCommandData commandData,
                              ref string message,
                              ElementSet elements)

        {
            UIApplication uiapp = commandData.Application;
            UIDocument uidoc = uiapp.ActiveUIDocument;
            Document doc = uidoc.Document;
            Settings documentSettings = doc.Settings;
            Categories categories = documentSettings.Categories;

            SortedList<string, Category> myCategories = new SortedList<string, Category>();

            foreach (Category c in categories)
            {
                myCategories.Add(c.Name, c);
            }

            myCategories.Clear();

            foreach (Category c in categories)
            {
                if (c.AllowsBoundParameters)
                myCategories.Add(c.Name, c);
            }
            UserWindow UserWindow = new UserWindow(myCategories);
            UserWindow.Show();

            
            ElementCategoryFilter filter = new ElementCategoryFilter(category);
            FilteredElementCollector collector = new FilteredElementCollector(doc);
            IList<Element> ListOfParameters = collector.WherePasses(filter);
            //this one doesn't work either
            //IList<Element> ListOfParameters = ListOfParameters.OfClass(typeof(category))
            return Result.Succeeded;
        }
    }
}

UserWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Autodesk.Revit.DB;

namespace CombineParameters

{
    /// <summary>
    /// Interaction logic for UserWindRoom.xaml
    /// </summary>
    public partial class UserWindow : Window
    {
        SortedList<string, Category> myCategories;

        public UserWindow(SortedList<string, Category> elements)
        {
            InitializeComponent();

            AllTheCategories.ItemsSource = elements;
            AllTheCategories.DisplayMemberPath = "Key";
            AllTheCategories.SelectionChanged += OnSelectionChanged;
        }
        public void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (AllTheCategories.SelectedItem is null)
            {
            }
            else if (AllTheCategories.SelectedItem is KeyValuePair<string, object> keyValuePair)
            {
                var category = (Category)keyValuePair.Value;
            }
        }
    }
}