TLDR:

• "bars": {"bar":[]}

  + "bars":{}

Long version:

In older ODL builds, JSON encoding for empty list inside a container did not have list name as kay at all. More recent builds, list name is there as a key, with [] as value. I believe the previous behavior was better, as it resulted in shorter JSON.

Standards and drafts are not very clear:
Example yang definition:
container bars {
list bar {
leaf foo

}
}

We want to encode empty list in json.
According to http://tools.ietf.org/html/rfc6020#section-7.8.5 the XML representation would be:
<bars>
</bars>
(note zero occurrences of <bar>)

This draft for json lists http://tools.ietf.org/html/draft-lhotka-netmod-yang-json-02#section-3.2.4 only tells what to do with one or more elements.

But for containers http://tools.ietf.org/html/draft-lhotka-netmod-yang-json-02#section-3.2.2 I believe these two mappings are implied:

<bars>
<bar/>
</bars>
would perhaps map to {"bars":{"bar":[]}}

but
<bars>
</bars>
would definitely map to {"bars:{}}

Once again, the previous behavior seem to be the correct one.