How i can CRCR to end of FromHeader?

Hi All,

I am User Agent Server to test any sip application.
To check the behavior of User Agent Client, user may add CRCR to the end 
of the From Header!!
How do i add CRCR to the end of From Header.

I have tried to add CRCR to the end of from header.
the bit of code is

public void AddCRCR(ArrayList CRCR)
    {
        Response response = SipServer.res;
        String name = (String) CRCR.get(0);
        FromHeader from = (FromHeader) response.getHeader(name);
        String input = from.toString();
        input = input + "\r\r";
}

Here input has the from header with CRCR character at the end of the header.
how i can set the that string into an response?

Thanks in advance..!!

Regards
Parasuraman