question: public synchronized OMGraphicList prepare ( ) { Projection p = getProjection ( ) ; TemporalOMGraphicList scenarioGraphics = null ; OMGraphicList list = getList ( ) ; if ( p != null ) { boolean DEBUG = logger . isLoggable ( Level . FINE ) ; if ( list == null || ! ( list instanceof TemporalOMGraphicList ) ) { scenarioGraphics = createData ( ) ; if ( scenarioGraphics == null ) { return null ; } } else { scenarioGraphics = new TemporalOMGraphicList ( list ) ; } long currentTime = getTime ( ) ; if ( DEBUG ) { logger . fine ( "EventLayer (" + getName ( ) + ") snapshot at " + currentTime ) ; } scenarioGraphics . generate ( p , currentTime ) ; if ( DEBUG ) { logger . fine ( "EventLayer (" + getName ( ) + ") setting list of " + scenarioGraphics . size ( ) + " scenario graphics" ) ; } } return scenarioGraphics ; }
target:  The main method call in the EventLayer that actually modifies the OMGraphics and updates the map.