public DataMutateResult appendGroup(Group group) {
        if (containsGroup(group)) {
            return DataMutateResult.FAIL_ALREADY_HAS;
        }

        List<String> before = ImmutableList.copyOf(this.groups);
        this.groups.add(group.getName());
        List<String> after = ImmutableList.copyOf(this.groups);

        this.plugin.getEventDispatcher().dispatchTrackAddGroup(this, group.getName(), before, after);
        return DataMutateResult.SUCCESS;
    }
Appends a group to the end of this track

@param group the group to append
@return the result of the operation
common/src/main/java/me/lucko/luckperms/common/model/Track.java