System.Net.CookieContainer.MergeUpdateCollections C# (CSharp) Method

        private void MergeUpdateCollections(CookieCollection destination, CookieCollection source, int port, bool isSecure, bool isPlainOnly) {

            // we may change it
            lock (source) {

                //cannot use foreach as we going update 'source'
                for (int idx = 0 ; idx < source.Count; ++idx) {
                    bool to_add = false;

                    Cookie cookie = source[idx];

                    if (cookie.Expired) {
                        //If expired, remove from container and don't add to the destination
                        source.RemoveAt(idx);
                        --m_count;
                        --idx;
                    }
                    else {
                        //Add only if port does match to this request URI
                        //or was not present in the original response
                        if(isPlainOnly && cookie.Variant != CookieVariant.Plain) {
                            ;//don;t add
                        }
                        else if(cookie.PortList != null)
                        {
                            foreach (int p in cookie.PortList) {
                                if(p == port) {
                                    to_add = true;
                                    break;
                                }
                            }
                        }
                        else {
                            //it was implicit Port, always OK to add
                            to_add = true;
                        }

                        //refuse adding secure cookie into 'unsecure' destination
                        if (cookie.Secure && !isSecure) {
                            to_add = false;
                        }

                        if (to_add) {
                            // In 'source' are already orederd.
                            // If two same cookies come from dif 'source' then they
                            // will follow (not replace) each other.
                            destination.InternalAdd(cookie, false);
                        }

                    }
                }
            }
        }