Hello dear Developers!

I want to set group to player with api, and add permission to player, but I don't find theese methods in API. What are the methods for this functions? Thanks for help!

You need to use User#setPermission to add the permissions / groups, and LuckPermsApi#getNodeFactory to build the node instances.

This is explained in detail here: https://github.com/lucko/LuckPerms/wiki/Developer-API , as well as in the javadocs.

can I give temp group? If I type "/lp user player parent addtemp group" the plugin don't add group to player, only the permission.

Yeah, you can set an expiry on the node when you build it with the Node.Builder class.

But the plugin only add the specified group permission, not add the group .

Group memberships are represented by permission nodes internally.