/// <summary>
 /// Determines whether the specified <paramref name="c"/> contains an entry with the specified <paramref name="key"/>.
 /// </summary>
 /// <param name="c">The <see cref="NameValueCollection"/> to search for <paramref name="key"/>.</param>
 /// <param name="key">The key to locate in <paramref name="c"/>.</param>
 /// <returns><c>true</c> if the specified <paramref name="c"/> contains an entry with the <paramref name="key"/>; otherwise, <c>false</c>.</returns>
 /// <remarks>This method performs an <see cref="StringComparison.OrdinalIgnoreCase"/> search for <paramref name="key"/>.</remarks>
 public static bool ContainsKey(NameValueCollection c, string key)
 {
     if (c == null)
     {
         return(false);
     }
     if (key == null)
     {
         return(false);
     }
     if (c.Get(key) == null)
     {
         return(EnumerableUtility.Contains(c.AllKeys, key, StringComparer.OrdinalIgnoreCase));
     }
     return(true);
 }