/// <summary>
/// Registers super properties without overwriting ones that have already been set.
/// </summary>
/// <param name="key">name of the property to register</param>
/// <param name="value">value of the property to register</param>
public static void RegisterOnce(string key, object value)
{
if (!OnceProperties.ContainsKey(key))
{
OnceProperties.Add(key, value);
}
}
