question: public synchronized static void destroy ( ) { if ( isInitialized ( ) ) { Map < String , ProcessEngine > engines = new HashMap < String , ProcessEngine > ( processEngines ) ; processEngines = new HashMap < String , ProcessEngine > ( ) ; for ( String processEngineName : engines . keySet ( ) ) { ProcessEngine processEngine = engines . get ( processEngineName ) ; try { processEngine . close ( ) ; } catch ( Exception e ) { log . error ( "exception while closing {}" , ( processEngineName == null ? "the default process engine" : "process engine " + processEngineName ) , e ) ; } } processEngineInfosByName . clear ( ) ; processEngineInfosByResourceUrl . clear ( ) ; processEngineInfos . clear ( ) ; setInitialized ( false ) ; } }
target:  closes all process engines. This method should be called when the server shuts down.