search for HeadingLevel throws exception

[SamBent]

• .NET Core Version: (e.g. 3.0 Preview1, or daily build number, use dotnet --info) 6.0.100-preview.7.21373.8
• Windows version: (winver) all
• Does the bug reproduce also in WPF for .NET Framework 4.8?: no (feature not included in 4.8)
• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? no

• Security issues and bugs should be reported privately, learn more via our responsible disclosure guidelines.

  Problem description: Use WPF UI Automation Client stack to search for an element with a certain value for the new HeadingLevel property. The first step is to create a Condition:

  PropertyCondition condition = new PropertyCondition(AutomationElement.HeadingLevelProperty, AutomationHeadingLevel.Level3);

  (The next step would be a call like element.FindFirst(TreeScope.Descendants, condition), but I can't even get that far.)

  Actual behavior:

  Exception thrown: 'System.ArgumentException' in UIAutomationClient.dll
  An exception of type 'System.ArgumentException' occurred in UIAutomationClient.dll but was not handled in user code
  PropertyCondition value for property 'AutomationElementIdentifiers.HeadingLevelProperty' must be 'HeadingLevel'.

Callstack:

    UIAutomationClient.dll!System.Windows.Automation.PropertyCondition.Init(System.Windows.Automation.AutomationProperty property, object val, System.Windows.Automation.PropertyConditionFlags flags)  Unknown
    UIAutomationClient.dll!System.Windows.Automation.PropertyCondition.PropertyCondition(System.Windows.Automation.AutomationProperty property, object value)   Unknown
>   FindHeadingLevel.dll!FindHeadingLevel.MainWindow.MainWindow() Line 14   C#

Expected behavior: No crash. (Note that the error message refers to a non-public type "HeadingLevel".)

Minimal repro: FindHeadingLevel.zip

[ryalanms]

@guimafelipe: This is a translation issue with the public and internal enum values.