Getting groups sorted by height from Vault(LuckPerms)

Hey. I am trying to make a list of players in groups sorted by the height of the group. Currently writing all the groups from the oldest to the youngest and I want it to sort the height.
I'm using Vault and permission plugin: LuckPerms.

Current class:

Code:

for(String s : this.plugin.permission.getGroups()) {
                for(Player player : Bukkit.getOnlinePlayers()) {
                    if(this.plugin.permission.getPrimaryGroup(player) == s) {
                            players.add(player.getDisplayName());
                    }
                }
                if(players.size() > 0) {
                    String listString = String.join(", ", players);
                    p.sendMessage(s + ": " + listString);
                }
                players.clear();
            }

How can I do this?