How to use join on nested association?

I have a complex structure which I'll simplify for this example:

```
class Site {
...
}

class Series {
Site primarySite
Set additionalSites
...
}

class Story {
Series series
...
}
```

I need to select all stories associated with a Site and make further more detailed selections with that.

First I select all series and that works fine using this:

```
def siteSeriesCriteria() {
return Series.where {
join("additionalSites", JoinType.LEFT)
or {
eq('primarySite', thisSite)
additionalSites {
eq('id', thisSite.id)
}
}
}
}

list = siteSeriesCriteria().id().list()
```
That produces the intended SQL:

```
select
this_.id as y0_
from
series this_
left outer join series_site additional3_ on
this_.id = additional3_.series_additional_sites_id
left outer join site additional1_ on
additional3_.site_id = additional1_.id
where
(this_.primary_site_id =?
or (additional1_.id =?))
```

But when I try to use the deeper nested level that doesn't work anymore:

```
def siteStoryCriteria() {
return Story.where {
series in siteSeriesCriteria().id()
}
}
list = siteStoryCriteria().id().list()
```

Now the join is no longer a left outer:
```
select
this_.id as y0_
from
story this_
where
this_.series_id in (
select
this_.id as y0_
from
series this_
inner join series_site additional3_ on
this_.id = additional3_.series_additional_sites_id
inner join site additional1_ on
additional3_.site_id = additional1_.id
where
(this_.primary_site_id =?
or (additional1_.id =?)))
```

I've read that join() only works on the tree root of the Criteria-tree. But how am I supposed to solve this?

I've tried to add
join("series.additionalSites", JoinType.LEFT)
to the nested criteria, but that doesn't work either. I'm stumped here...

Start by reproducing the Series.where and Story.where criteria shown in the issue, including the generated SQL for the nested association query. Trace how join("additionalSites", JoinType.LEFT) is applied inside siteSeriesCriteria and determine whether a supported nested-criteria approach can preserve the left outer join; done means a documented or tested approach produces the intended story results.

Written by the indexing model from the issue text.