Helper method to Replace/Remove characters that do not match the Regular Expression

I have a few fields, that use regEx for validation. In case if provided field has unaccepted characters, I don't want to reject the whole field, as most of validators do, but just remove invalid characters.
 I am expecting to keep only Character Classes for allowed characters and created a helper method to strip unaccepted characters.
The allowed pattern should be in Regex format, expect them wrapped in square brackets. function will insert a tilde after opening squere bracket , according to
[^ ] at the start of a character class negates it - it matches characters not in the class.
I anticipate that it could work not for all RegEx describing valid characters sets,but it works for relatively simple sets, that we are using.
        /// <summary>
               /// Replaces  not expected characters.
               /// </summary>
               /// <param name="text"> The text.</param>
               /// <param name="allowedPattern"> The allowed pattern in Regex format, expect them wrapped in brackets</param>
               /// <param name="replacement"> The replacement.</param>
               /// <returns></returns>
               /// //
               //[^ ] at the start of a character class negates it - it matches characters not in the class.
               //Replace/Remove characters that do not match the Regular Expression
               static public string ReplaceNotExpectedCharacters( this string text, string allowedPattern,string replacement )
                     allowedPattern = allowedPattern.StripBrackets( "[", "]" );
                      //[^ ] at the start of a character class negates it - it matches characters not in the class.
                      var result = Regex .Replace(text, @"[^" + allowedPattern + "]", replacement);
                      return result;

static public string RemoveNonAlphanumericCharacters( this string text)
                      var result = text.ReplaceNotExpectedCharacters(NonAlphaNumericCharacters, "" );
                      return result;
        public const string NonAlphaNumericCharacters = "[a-zA-Z0-9]";

There are a couple of functions from my StringHelper class ,
 that are used here.
               /// <summary>
               /// 'StripBrackets checks that starts from sStart and ends with sEnd (case sensitive).
               ///           'If yes, than removes sStart and sEnd.
               ///           'Otherwise returns full string unchanges
               ///           'See also MidBetween
               /// </summary>
               /// <param name="str"></param>
               /// <param name="sStart"></param>
               /// <param name="sEnd"></param>
               /// <returns></returns>
               public static string StripBrackets( this string str, string sStart, string sEnd)
                      if (CheckBrackets(str, sStart, sEnd))
                           str = str.Substring(sStart.Length, (str.Length - sStart.Length) - sEnd.Length);
                      return str;
               public static bool CheckBrackets( string str, string sStart, string sEnd)
                      bool flag1 = (str != null ) && (str.StartsWith(sStart) && str.EndsWith(sEnd));
                      return flag1;

               public static string WrapBrackets( string str, string sStartBracket, string sEndBracket)
                      StringBuilder builder1 = new StringBuilder(sStartBracket);
                      return builder1.ToString();

maxItemsInObjectGraph limit required to be changed for server and client

We have a wcf service, that expects to return a huge XML data. It worked ok in testing, but in production it failed with error  "Maximum number of items that can be serialized or deserialized in an object graph is '65536'. Change the object graph or increase the MaxItemsInObjectGraph quota."

The MSDN article about   dataContractSerializer xml configuration  element  correctly  describes maxItemsInObjectGraph attribute default as 65536, but documentation for of the 

DataContractSerializer.MaxItemsInObjectGraph property and DataContractJsonSerializer.MaxItemsInObjectGraph Property 

are talking about Int32.MaxValue, which causes confusion, in particular because Google shows properties articles before configuration articles.

When we changed the value in WCF service configuration, it didn't help, because the similar change must be ALSO done on client.

There are similar posts:

You need to set the MaxItemsInObjectGraph on the dataContractSerializer using a behavior on both the client and service. See  for an example.

 I had forgot to place this setting in my client app.config file.

It seems that DataContractJsonSerializer.MaxItemsInObjectGraph has actual default 65536, because there is no configuration for JSON serializer, but  it complains about the limit.

I believe that MS should clarify the properties documentation re default limit and make more specific error messages to distinguish server side and client side errors.

Note, that as a workaround it's possible to use commonBehaviors section which can be defined only in machine.config:
<dataContractSerializer maxItemsInObjectGraph="..." />