Disable natural spawning of mobs in region

[2tbc1887]

Is your feature request related to a problem? Please describe.
I have a mob arena in my map, and would like to disable natural mob spawning whilst also allowing command block / egg spawning

Describe the solution you'd like
In addition to the mob-spawning flag, perhaps natural-mob-spawning or commandblock-spawning

Describe alternatives you've considered
Researched, only found dead plugins

Additional context

[AlvinVrolijk]

+1

[suerion]

What mob plugin did You use?