[Windows] - Picker on windows shows "Microsoft.Maui.Controls.Picker" …

…if ItemsSource has an empty string (#24276)

* fix-8845-Picker on windows shows "Microsoft.Maui.Controls.Picker" if ItemsSource has an empty string

* Added image for test case

* Updated Script file

* Modified test case

* modified test case

* Modified test case

* Modified test case

* Modified test case

* Modified code changes

src/Controls/tests/TestCases.HostApp/Issues/Issues8845.xaml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             Title="Issue 8845"
+             x:Class="Maui.Controls.Sample.Issues.Issue8845">
+
+  <VerticalStackLayout>
+    <Picker AutomationId="MauiPicker1" x:Name="picker1" ItemDisplayBinding="{Binding DisplayName}"/>
+    <Picker AutomationId="MauiPicker2" x:Name="picker2" ItemDisplayBinding="{Binding DisplayName}"/>
+    <Button AutomationId="UpdateButton" Text="Update" Clicked="Button_Clicked"/>
+  </VerticalStackLayout>
+
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issues8845.xaml.cs

@@ -0,0 +1,29 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 8845, "Picker on windows shows \"Microsoft.Maui.Controls.Picker\" if ItemsSource has an empty string", PlatformAffected.UWP)]
+	public partial class Issue8845 : ContentPage
+	{
+		public Issue8845()
+		{
+			InitializeComponent();
+			var items = new List<object>
+				{
+					new { DisplayName = (string)null!},
+					new { DisplayName = "Not null"},
+				};
+			picker1.ItemsSource = items;
+			picker2.ItemsSource = items;
+		}
+
+		private void Button_Clicked(object sender, EventArgs e)
+		{
+			picker1.SelectedIndex = 0;
+			picker2.SelectedIndex = 1;
+		}
+
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue8845.cs

@@ -0,0 +1,30 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue8845 : _IssuesUITest
+	{
+		public Issue8845(TestDevice testDevice) : base(testDevice)
+		{
+		}
+
+		public override string Issue => "Picker on windows shows \"Microsoft.Maui.Controls.Picker\" if ItemsSource has an empty string";
+
+		[Test]
+		[Category(UITestCategories.Picker)]
+		public void PickerShouldDisplayValueFromItemDisplayBinding()
+		{
+			App.WaitForElement("UpdateButton");
+			App.Tap("UpdateButton");
+
+			var picker1Text = App.WaitForElement("MauiPicker1").GetText();
+			var picker2Text = App.WaitForElement("MauiPicker2").GetText();
+
+			Assert.That(picker1Text, Is.Empty);
+			Assert.That(picker2Text, Is.EqualTo("Not null"));
+		}
+	}
+}

src/Core/src/Platform/Windows/PickerExtensions.cs

@@ -8,12 +8,11 @@ public static class PickerExtensions
 	{
 		public static void UpdateTitle(this ComboBox nativeComboBox, IPicker picker)
 		{
-			nativeComboBox.Header = null;
+			nativeComboBox.Header = string.IsNullOrEmpty(picker.Title) ? null : picker;
 
 			nativeComboBox.HeaderTemplate = string.IsNullOrEmpty(picker.Title) ? null :
 				(UI.Xaml.DataTemplate)UI.Xaml.Application.Current.Resources["ComboBoxHeader"];
 
-			nativeComboBox.DataContext = picker;
 		}
 
 		public static void UpdateBackground(this ComboBox nativeComboBox, IPicker picker)