private Task <Document> AddSummaryCommentAsync(Document document, BaseTypeDeclarationSyntax declaration, CancellationToken c)
{
var leadingTrivias = declaration.GetLeadingTrivia();
var whitespaceCount = leadingTrivias[leadingTrivias.Count - 1].Span.Length;
var newDeclaration = declaration.WithLeadingTrivia(
AnalyzerUtil.GetNewLeadingTriviaWithSummary(leadingTrivias, summaryComments, whitespaceCount));
return(AnalyzerUtil.ReplaceNode(declaration, newDeclaration, document));
}