modules/prebidServerBidAdapter/index.js
function doPreBidderSync(type, url, bidder, done) {
  if (_s2sConfig.syncUrlModifier && typeof _s2sConfig.syncUrlModifier[bidder] === 'function') {
    const newSyncUrl = _s2sConfig.syncUrlModifier[bidder](type, url, bidder);
    doBidderSync(type, newSyncUrl, bidder, done)
  } else {
    doBidderSync(type, url, bidder, done)
  }
}
function doPreBidderSync(type, url, bidder, done) {
  if (_s2sConfig.syncUrlModifier && typeof _s2sConfig.syncUrlModifier[bidder] === 'function') {
    const newSyncUrl = _s2sConfig.syncUrlModifier[bidder](type, url, bidder);
    doBidderSync(type, newSyncUrl, bidder, done)
  } else {
    doBidderSync(type, url, bidder, done)
  }
}
function doPreBidderSync ( type , url , bidder , done ) { if ( _s2sConfig . syncUrlModifier && typeof _s2sConfig . syncUrlModifier [ bidder ] === 'function' ) { const newSyncUrl = _s2sConfig . syncUrlModifier [ bidder ] ( type , url , bidder ) ; doBidderSync ( type , newSyncUrl , bidder , done ) } else { doBidderSync ( type , url , bidder , done ) } }
Modify the cookie sync url from prebid server to add new params.

@param {string} type the type of sync, "image", "redirect", "iframe"
@param {string} url the url to sync
@param {string} bidder name of bidder doing sync for
@param {function} done an exit callback; to signify this pixel has either: finished rendering or something went wrong
Modify the cookie sync url from prebid server to add new params .