Fix LocalizableString to work with internal ResourceType (#111130)

* Fix LocalizableString to work with internal ResourceType

Removed check for Resource Type to be public.
Added test for DisplayAttribute to ensure it works with with internal Resource Type.

* remove the line numbers from the DisplayAttributeTests.cs file

Author: uo1

src/libraries/System.ComponentModel.Annotations/src/System/ComponentModel/DataAnnotations/LocalizableString.cs

@@ -128,9 +128,8 @@ private void ClearCache()
                     // We need to detect bad configurations so that we can throw exceptions accordingly
                     var badlyConfigured = false;
 
-                    // Make sure we found the property and it's the correct type, and that the type itself is public
-                    if (!_resourceType.IsVisible || property == null ||
-                        property.PropertyType != typeof(string))
+                    // Make sure we found the property and it's the correct type
+                    if (property == null || property.PropertyType != typeof(string))
                     {
                         badlyConfigured = true;
                     }

src/libraries/System.ComponentModel.Annotations/tests/System/ComponentModel/DataAnnotations/DisplayAttributeTests.cs

@@ -191,5 +191,20 @@ public void Order_Get_Set(int value)
             Assert.Equal(value, attribute.Order);
             Assert.Equal(value, attribute.GetOrder());
         }
+ 
+        [Fact]
+        public void LocalizableString_WorksWithInternalResourceType()
+        {
+            DisplayAttribute attribute = new DisplayAttribute();
+            attribute.ResourceType = typeof(InternalResourceType);
+            attribute.Name = nameof(InternalResourceType.PublicProperty);
+
+            Assert.Equal(InternalResourceType.PublicProperty, attribute.GetName());
+        }
+
+        internal class InternalResourceType
+        {
+            public static string PublicProperty => "Internal Resource with Public Property";
+        }
     }
 }