The final 2 default converters are for maps and collections:
<convert converter="collection" match="java.util.Collection"/>
and
<convert converter="map" match="java.util.Map"/>
Generally speaking these converters will be able to recursively convert their contents.
There is a catch for these 2 however:
There is no way of knowing the underlying type of the collection just using reflection. So the 2 converters above can convert from any collection to something meaningful in JavaScript, however there is no way to know what sort of Collection to convert to going the other way.
Since we can't work it out automatically we may need to use the special signatures syntax in the dwr.xml file to allow us to hint types to the conversion process.