ItemPackageEvent.cs

public class ItemPackageEvent
{
    public void OnPackageInstallItemsEndHandler(object sender, EventArgs e)
    {
        if (e == null)
        {
            return;
        }

        SitecoreEventArgs sitecoreEventArgs = e as SitecoreEventArgs;

        if (sitecoreEventArgs == null || sitecoreEventArgs.Parameters == null || sitecoreEventArgs.Parameters.Length != 1)
        {
            return;
        }

        InstallationEventArgs parameter = sitecoreEventArgs.Parameters[0] as InstallationEventArgs;
        
        // The paramter.ItemsToInstall provides the list of items together with the item id, language that have been installed on the CMS
        // Check for null in case no item is available.
        if (parameter == null || parameter.ItemsToInstall == null)
        {
            return;
        }

        // Implementation goes here for processing the list of items
    }
}