Issue with UTCTime to Posix

It would appear that there are default alterations `UTCTime` that convert fields into `Posix`.
That's great, but it doesn't seem to be followed through in the generated code.

For example, it will correctly rename the field, but it does not import Time and uses a decoder called `jsonDecPosix` (autogenerated naming). That decoder does not exist.

Is there another way around this issue? Is there something I'm missing? We are using servant-elm but I tried directly through elm-bridge and got the same results.

This is an example (ignore the silly naming) from the generated code:
```
type alias FweetDto =
{ fwuser: FwuserDto
, fwody: String
, fwimestamp: Posix
}

jsonDecFweetDto : Json.Decode.Decoder ( FweetDto )
jsonDecFweetDto =
Json.Decode.succeed (\pfwuser pfwody pfwimestamp -> {fwuser = pfwuser, fwody = pfwody, fwimestamp = pfwimestamp})
|> required "fwuser" (jsonDecFwuserDto)
|> required "fwody" (Json.Decode.string)
|> required "fwimestamp" (jsonDecPosix)```