Would it be possible to have an option to just stop the server if it is empty for X number of minutes?

That way the server would shut itself down shortly after all the player leave... seems like a nice environmentally friendly option =] It's what I have been searching for and how I ended up on this plug-in to begin with... Already able to start it up on demand using a Velocity plugin...

Definitely something I can look into adding in 0.1.2!

Temporary fix which tries to shutdown the server 4X an hour:

{
"serverLang": "en_us",
"stopWhenPlayersOnline": false,
"disableUpdateCheck": false,
"enableMonday": true,
"mondayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"mondayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableTuesday": true,
"tuesdayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"tuesdayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableWednesday": true,
"wednesdayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"wednesdayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableThursday": true,
"thursdayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"thursdayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableFriday": true,
"fridayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"fridayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableSaturday": true,
"saturdayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"saturdayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46],
"enableSunday": true,
"sundayHour": [0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23],
"sundayMinute": [1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46, 1, 16, 31, 46]
}

Thanks for the assistance in Discord!

A nice addition to this would be adding a command that lets players temporarily disable server auto shutdown. Something along the lines of /keepalive [time]|indefinite|cancel, probably behind a permission.