...
Start JAS3 and open the file from the LCSim Event Browser Tutorial using the File -> Open command. You should If (and only if) you have both the LCIO and the org.lcsim plugin installed, you will be asked which one to use. In this case select the org.lcsim plugin.
If you now see the record loop commands and the name of the file displayed in the record source drop-down box, the file is loaded OK.
Opening the Sample Driver
...