private ICommandResult RetrieveLabelList(IEnumerable<string> issueKeys)
{
var labels = new HashSet<string>();
return ExecuteCommand(
issueKeys,
issueKey =>
{
var issue = _jira.GetIssue(issueKey);
Array.ForEach(LabelFormatConveter.From(issue).To(a => a.ToArray()), label => labels.Add(label));
return FormatOutputMessage(issueKey, LabelFormatConveter.FromIssue(issue));
},
() => labels);
}