HttpContext.Current.Request.QueryString.AllKeys 返回的大小写， 飘忽不定。

HttpContext.Current.Request.QueryString.AllKeys 返回的大小写， 飘忽不定。

E:\myapp\MS_Symbols\src\source\FXUpdate3074\1.1\DEVDIV\depot\DevDiv\releases\whidbey\QFE\ndp\fx\src\xsp\System\Web\OutputCacheModule.cs\6\OutputCacheModule.cs

internal static string CreateOutputCachedItemKey

                    /* handle all params case (VaryByParams[*] = true) */
                    if (getAllParams && col.Count > 0) {
                        a = col.AllKeys;
                        for (i = a.Length - 1; i >= 0; i--) {
                            if (a[i] != null)
                                a[i] = CultureInfo.InvariantCulture.TextInfo.ToLower(a[i]);
                        }
 
                        Array.Sort(a, InvariantComparer.Default);
                    }

不明白， 为什么要 ToLower ？！