VSTHRD010 for callers of method that switches to main thread

Bug description

Callers to this method have warning VSTHRD010

        private void UpdateColoursFromFontsAndColors()
        {
            ThreadHelper.JoinableTaskFactory.Run(async () =>
            {
                await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
                var success = fontAndColorStorage.OpenCategory(ref categoryWithCoverage, storeFlags);
                if (success == VSConstants.S_OK)
                {
                    CoverageTouchedArea = GetColor("Coverage Touched Area");
                    CoverageNotTouchedArea = GetColor("Coverage Not Touched Area");
                    CoveragePartiallyTouchedArea = GetColor("Coverage Partially Touched Area");
                }
                fontAndColorStorage.CloseCategory();
                //throw ?
                requiresFromFontsAndColours = false;
            });
            
        }

        private System.Windows.Media.Color GetColor(string displayName)
        {
            ThreadHelper.ThrowIfNotOnUIThread();
            var touchAreaInfo = new ColorableItemInfo[1];
            var getItemSuccess = fontAndColorStorage.GetItem(displayName, touchAreaInfo);
            if (getItemSuccess == VSConstants.S_OK)
            {
                return ParseColor(touchAreaInfo[0].crBackground);
            }
            throw new Exception("Failed to get color");
        }

Remove the calls to GetColor and no warnings.
Make GetColor a local function ( without ThreadHelper.ThrowIfNotOnUIThread() ) and no warnings

Expected behavior

No warnings

Actual behavior

warnings

• Version used: Microsoft.VisualStudio.SDK - 17.0.31902.203
• Application (if applicable):

Additional context

Add any other context about the problem here.

Start by reproducing VSTHRD010 with the UpdateColoursFromFontsAndColors and GetColor methods shown in the issue. Trace how the analyzer handles the JoinableTaskFactory.Run call, SwitchToMainThreadAsync, and the local-function variant, then verify that the reported caller warnings are eliminated without introducing new warnings.