[Bug] Attached Collection Property return the property for all views and not just the one that is calling

[MathewLC]

Description

When having Collection like IList as an attached property, GetValue return the value for all views that has this property instead of return just the property related to the view that is calling GetValue.

Steps to Reproduce

1. Run the sample.
2. Click on the button that will execute code to get the properties to different views.

Expected Behavior

Method return property related only to itself.

Actual Behavior

view.GetValue return properties to all views that has it.

Basic Information

• Version with issue: Xamarin.Forms (4.4.0.991265)

Reproduction Link

Sample with Issue

[jfversluis]

Confirmed this is happening. Both on iOS and Android, which makes sense since its shared code.

I went back to 3.6 and there it also happens. So I'm assuming this has been in there forever.

[GalaxiaGuy]

@MathewLC @StephaneDelcroix Is this really a bug? It seems to happen because the default value, a new List<MyCustomClass> is shared between uses of the bindable property.

If I change it to use defaultValueCreator: _ => new List<MyCustomClass>() everything seems to work fine.