Get string truncated to max length
If you're using C# 6.0, I believe you can drop the null-check:

public static string WithMaxLength(this string value, int maxLength)
{
    return value?.Substring(0, Math.Min(value.Length, maxLength));
}


Other than that, it's like Jeroen said: that's pretty much as good as it gets.

The class and parameter naming is exactly as I'd have it, and the name of the extension method is decent, although I'd try to find a name that better indicates that truncation will occur when value is longer than maxLength... but WithMaxLength isn't a bad name.