Fix #5335 - Multiple Media Picker not available as macro parameter

(cherry picked from commit 1f2c4e38ac)

src/Umbraco.Core/Constants-PropertyEditors.cs

@@ -96,6 +96,11 @@ namespace Umbraco.Core
                 /// </summary>
                 public const string MediaPicker = "Umbraco.MediaPicker";
 
+                /// <summary>
+                /// Multiple Media Picker.
+                /// </summary>
+                public const string MultipleMediaPicker = "Umbraco.MultipleMediaPicker";
+
                 /// <summary>
                 /// Member Picker.
                 /// </summary>

src/Umbraco.Web/PropertyEditors/ParameterEditors/MultipleMediaPickerParameterEditor.cs

@@ -0,0 +1,27 @@
+using Umbraco.Core;
+using Umbraco.Core.Logging;
+using Umbraco.Core.PropertyEditors;
+
+namespace Umbraco.Web.PropertyEditors.ParameterEditors
+{
+    /// <summary>
+    /// Represents a multiple media picker macro parameter editor.
+    /// </summary>
+    [DataEditor(
+        Constants.PropertyEditors.Aliases.MultipleMediaPicker,
+        EditorType.MacroParameter,
+        "Multiple Media Picker",
+        "mediapicker",
+        ValueType = ValueTypes.Text)]
+    public class MultipleMediaPickerParameterEditor : DataEditor
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MultipleMediaPickerParameterEditor"/> class.
+        /// </summary>
+        public MultipleMediaPickerParameterEditor(ILogger logger)
+            : base(logger)
+        {
+            DefaultConfiguration.Add("multiPicker", "1");
+        }
+    }
+}

src/Umbraco.Web/Umbraco.Web.csproj

@@ -224,6 +224,7 @@
     <Compile Include="Mvc\SurfaceControllerTypeCollectionBuilder.cs" />
     <Compile Include="Mvc\ValidateUmbracoFormRouteStringAttribute.cs" />
     <Compile Include="Profiling\WebProfilingController.cs" />
+    <Compile Include="PropertyEditors\ParameterEditors\MultipleMediaPickerParameterEditor.cs" />
     <Compile Include="PublishedCache\NuCache\PublishedSnapshotServiceOptions.cs" />
     <Compile Include="PublishedCache\NuCache\Snap\GenObj.cs" />
     <Compile Include="PublishedCache\NuCache\Snap\GenRef.cs" />