How to Filter the items in WPF AutoComplete Control?

//Code Explains how to filter the items in Autocomplete control
<Window x:Class="AutoComplete.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:AutoComplete"
xmlns:syncfusion="http://schemas.syncfusion.com/wpf"
Title="MainWindow" Height="350" Width="525">
 <Grid> 
   <syncfusion:SfAutocomplete x:Name="Autocomplete" 

            AutoCompleteSource ="{Binding item}"

            SearchItemPath="item" 

            SuggestionMode="Contains" 

            AutoCompleteMode="Suggest" 

            HorizontalAlignment="Center" VerticalAlignment="Top"

            Height="40" Width="150" ​Margin="176,125,177,0"/>

    </Grid>

​​</Window>

//Code explains how to filter the items in AutoComplte control
namespace AutoComplete
{
 public partial class MainWindow : Window
 {
     AutoCompleteList obj = new AutoCompleteList();
     public MainWindow()
     {
          InitializeComponent();
          Autocomplete.AutoCompleteSource = obj;
     }
  }

public class Autocomplete
{
      public string item { get; set; 
}

public class AutocompleteList : List<AutoComplete>
{
     public AutoCompleteList()
     {
          this.Add(new Autocomplete() { item = "item 1" });
          this.Add(new Autocomplete() { item = "item 2" });
          this.Add(new Autocomplete() { item = "item 3" });
          this.Add(new Autocomplete() { item = "item 4" });
          this.Add(new Autocomplete() { item = "item 5" });
          this.Add(new Autocomplete() { item = "item 6" });
      }
   }
}