private void BuildWarningSection(IEnumerable<GitHubIssue> invalidIssues)
{
if(!invalidIssues.Any())
return;
_markupStringBuilder.Append(_renderer.RenderHeader("Warning: labeled issues without milestone detected"));
_markupStringBuilder.Append(_renderer.RenderNewParagraph());
foreach(var issue in invalidIssues)
_markupStringBuilder.Append(_renderer.RenderListItem(_renderer.RenderUrl(issue.Title, issue.Html_Url)));
}