Moshi support fails when serializing collections

[http4k]

Moshi support fails when serializing collections

[daviddenton]

On further inspection, this seems to be the same issue that we have when deserialising raw lists using the Jackson auto-conversion. Lists do seem to behave correctly when nested inside other objects.

We found that the way around this with Jackson was to use arrays instead of raw lists - this also worked with the lens mechanism and works with Moshi:
Body.auto<Array<Whatever>>().toLens()

Without using the array workaround, attempting to deserialise a data class like this:
```data class ArbObject(val string: String, val child: ArbObject?, val numbers: List, val bool: Boolean)````
.. using a standard Moshi adapter fromJson() call results in an ArrayList<LinkedTreeHashMap> being created.

I've also added the missing fromJsonString method to Moshi which allows you to pass the class to the serialisation method should the above

[daviddenton]

Changes are in 3.6.1