public bool ExistsImage(Topic topic, string imageName)
{
#region validation
if (topic == null)
{
throw new ArgumentNullException(nameof(topic));
}
if (string.IsNullOrEmpty(imageName))
{
throw new ArgumentNullException(nameof(imageName));
}
#endregion
string[] imageFolder = GetImageFolder(topic);
return(FileContainer.ExistsFile(imageName, imageFolder));
}