Replace empty strings with `null` recursively in .NET configuration sections

ChangeEmptyStringToNull.cs

private static void ChangeEmptyStringToNull(IConfigurationSection configSection)
{
    if (configSection == null) return;
    if (configSection.Value == "") configSection.Value = null;
    foreach (var childConfigSection in configSection.GetChildren())
    {
        ChangeEmptyStringToNull(childConfigSection);
    }
}