question: public static void stopTimer ( String name ) { long stopTime = System . nanoTime ( ) ; Long startTime = openTimers . remove ( name ) ; if ( startTime == null ) { throw new IllegalArgumentException ( "timer does not exist" ) ; } SummaryStatistics statistics = data . get ( name ) ; if ( statistics == null ) { statistics = new SummaryStatistics ( ) ; data . put ( name , statistics ) ; } statistics . addValue ( stopTime - startTime ) ; }
target:  Stops the timer with the specified name.