WLC 3750G-WS-S50 upgrade path

Someone needs to upgrade the WLC 3750G-WS-S50 from 4.2.99.0 to 7.0.240, it is necessary to find the upgrade path. Here is the path:

Finally, i don't want to take any risk. I upgrade from 4 to 5, 5 to 6, and 6 to 7. It is totally waste of time.... but successful :)