org.netbeans.api.db.explorer.DatabaseException: connection already exists
        at org.netbeans.modules.db.explorer.infos.RootNodeInfo.addConnection(RootNodeInfo.java:238)
        at org.netbeans.api.db.explorer.ConnectionManager.addConnection(ConnectionManager.java:145)
        at org.netbeans.modules.visualweb.dataconnectivity.utils.SampleDatabaseCreator.registerDatabase(SampleDatabaseCreator.java:144)
        at org.netbeans.modules.visualweb.dataconnectivity.utils.SampleDatabaseCreator.createAll(SampleDatabaseCreator.java:94)
        at org.netbeans.modules.visualweb.dataconnectivity.naming.DerbyWaiter$2.run(DerbyWaiter.java:125)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)