Converting from IEnumerable<KVP> to a dictionary is dangerous because IEnumerable<KVP> allows duplicate keys whereas dictionary does not. We should change the properties parameter to be a dictionary instead of IEnumerable<KVP> to avoid these kinds of problems.

It is safe if you use a foreach loop and set the key each time, so last key wins. My preference for IEnumerable is only to follow the "take in least derived, return most derived" principal. But I am not unmoving in that. If you disagree and want IDictionary, that is fine.

Thanks, Chris and Jacob. I updated this to be Dictionary. Because to write a foreach loop, I have to either grant Properties private set, or adding a new field to store this and then pass the value to Properties. Just feel like using Dictionary directly here seems like a more straightforward and cleaner way in this case. Let me know if you prefer others.

I am okay with going back to dictionary, but I don't see why you need a private set. The following is valid without any setter on Properties:

this.Properties = new();
foreach ((string key, object? value) in properties)
{
    this.Properties[key] = value;
}

or if this.Properties is IReadOnlyDictionary<string, object?>, then you can do this:

Dictionary<string, object?> props = new();
foreach ((string key, object? value) in properties)
{
    props[key] = value;
}

this.Properties = props;