question: public static String findPreferredIDP ( String realm , HttpServletRequest request ) { if ( request == null ) { return null ; } String succinctID = request . getParameter ( IFSConstants . PROVIDER_ID_KEY ) ; if ( ( succinctID == null ) || succinctID . length ( ) == 0 ) { debug . message ( "FSUtils.findPreferredIDP::Pref IDP not found." ) ; return null ; } succinctID = succinctID . trim ( ) ; String preferredSuccinctId = null ; StringTokenizer st = new StringTokenizer ( succinctID , " " ) ; while ( st . hasMoreTokens ( ) ) { preferredSuccinctId = st . nextToken ( ) ; if ( ( preferredSuccinctId . length ( ) < 28 ) && st . hasMoreTokens ( ) ) { preferredSuccinctId = preferredSuccinctId + "+" + st . nextToken ( ) ; } } preferredSuccinctId = SAMLUtils . byteArrayToString ( Base64 . decode ( preferredSuccinctId ) ) ; return getProviderIDFromSuccinctID ( realm , preferredSuccinctId ) ; }
target:  Finds the preferred IDP from the HttpServletRequest.