This is how SubServers will implement the Validator API that I suggested. I had to make some assumptions though (like how I don't expect BungeeCord's api to have a setTabValidator() method).
/sub reload - can now perform soft reloads
/greload - still performs hard resets
Soft Reloads mean that SubServers will load new data from the config and attempt to merge it with what is already in memory.
This is good if you need to make some quick changes, since it will only stop servers if a major change has been made to them.
However, this has the potential to cause issues, which is why the Hard Reset will continue to be tied to bungeecord command.