Potential fix to query multiple channels

[AWAS666]

This might be wrong, I did a quick and dirty example in github.dev ;)
But should get the idea accross what's needed for #408

Also there might be other endpoints here with the same issue

[Hampo]

Thanks for your contribution, unfortunately that code won't work as you're encapsulating getParams inside for the foreach loop. For a better idea on how best to implement this, look at something like GetVIPsAsync's userIds in the same file.

Additionally, for backwards compatibility, it might be worth adding something like:

public Task<GetChannelInformationResponse> GetChannelInformationAsync(string broadcasterId, string accessToken = null) => GetChannelInformationAsync(new List<string>() { broadcasterId }, accessToken);

[Mahsaap]

Looks good to me but please target Dev branch.
And the getparams like Hampo stated, needs to be outside the loop

[Hampo]

Not tested, but something like:

public Task<GetChannelInformationResponse> GetChannelInformationAsync(List<string> broadcasterIds, string accessToken = null)
{
    if (broadcasterIds.Count == 0 || broadcasterIds.Count > 100)
        throw new BadParameterException("boardcasterIds must contain between 1 and 100 broadcasterIds.");

    var getParams = broadcasterIds.Select(broadcasterId => new KeyValuePair<string, string>("broadcaster_id", broadcasterId)).ToList();

    return TwitchGetGenericAsync<GetChannelInformationResponse>("/channels", ApiVersion.Helix, getParams, accessToken);
}

• Changed .Count() from the Linq function to the List's property Count.
• Used Linq to generate the getParams List from the broadcasterIds parameter.

[AWAS666]

well that wasn't the brightest idea, I'll just create a new pr so this isn't a mess :)