want to develop a add-on that can create a group inside a space.\

[zolibra]

is there any way to do this?

I saw some java api support this, like createGroup...

[Nic Brough -Adaptavist-]

Groups do not belong to spaces, so no.  Unless you mean you want to create some sort of functionality which allows you to build lists of users inside a space and then write something else that uses these lists.

You can write code that would create groups and then add them to space permissions of course.