/// <summary>
/// Initializes a new instance of the <see cref="Header"/> class.
/// </summary>
/// <param name="headerItem">The item from this header.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="headerItem"/> is <see langword="null"/>.
/// </exception>
public Header(HeaderItem headerItem)
{
if (headerItem == null)
{
throw new ArgumentNullException(nameof(headerItem), "The header item cannot be null.");
}
Items = ListUtility.CreateSingleElementList(headerItem).AsReadOnly();
}