How to add items to WPF Grid

// One single entry
public class Entry : INotifyPropertyChanged
{
    private string key;
    private string val;
 
    public String Key
    {
        get { return this.key; }
        set
        {
            if (this.key == value)
                return;
 
            this.key = value;
            OnPropertyChanged("Key");
        }
    }
    public String Value 
    { 
        get
        {
            return this.val;
        } 
        set
        {
            if (this.val == value)
                return;
 
            this.val = value;
            OnPropertyChanged("Value");
        } 
    }
 
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }
 
    public event PropertyChangedEventHandler PropertyChanged;
}
 
// Collection of entries
public class EntryCollection : ObservableCollection<Entry>
{
    
}
 
// Just a mock for retrieving test data
public class MockEntries
{
    public EntryCollection GetDemoEntries()
    {
        EntryCollection col = new EntryCollection()
          {
                new Entry { Key="Key1", Value="Value1"},
                new Entry { Key="Key2", Value="Value2"},
                new Entry { Key="Key3", Value="Value3"},
                new Entry { Key="Key4", Value="Value4"},
                new Entry { Key="Key5", Value="Value5"},
          };
        return col;
    }
}
//---------- Window
 
public Window1()
{
    InitializeComponent();
 
    MockEntries entryMock = new MockEntries();
    this.DataContext = entryMock.GetDemoEntries();
}
 
//---------- XAML
 
<DockPanel>
    <grid:DataGrid AutoGenerateColumns="False" ItemsSource="{Binding .}">
        <grid:DataGrid.Columns>
            <grid:DataGridTextColumn Binding="{Binding Path=Key}" Header="Key"/>
            <grid:DataGridTextColumn Binding="{Binding Path=Value}" Header="Value"/>
        </grid:DataGrid.Columns>
    </grid:DataGrid>
</DockPanel>

                                              

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