Autogenerated code fails to compile if -Ywarn and fatal warnings is enabled

If you define your scalac setting in your project like so, for example

scalacOptions in ThisBuild ++= Seq(
"-Ywarn-unused"
)

then you are forced to separate your stub / autogen code into separate submodules, which might not be desirable, due to unused warnings:

```
rror] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:13:51: Unused import
[error] import akka.stream.scaladsl.{ FileIO, Keep, Sink, Source }
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:14:18: Unused import
[error] import akka.util.ByteString
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:15:15: Unused import
[error] import cats.{ Functor, Id }
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:15:24: Unused import
[error] import cats.{ Functor, Id }
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:17:23: Unused import
[error] import cats.implicits._
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:19:23: Unused import
[error] import scala.language.implicitConversions
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:20:16: Unused import
[error] import java.io.File
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:21:22: Unused import
[error] import java.security.MessageDigest
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:22:36: Unused import
[error] import java.util.concurrent.atomic.AtomicReference
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:23:21: Unused import
[error] import scala.util.{ Failure, Success }
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Client.scala:23:30: Unused import
[error] import scala.util.{ Failure, Success }
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:2:17: Unused import
[error] import io.circe._
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:3:24: Unused import
[error] import io.circe.syntax._
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:4:34: Unused import
[error] import io.circe.generic.semiauto._
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:5:23: Unused import
[error] import cats.implicits._
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:6:18: Unused import
[error] import cats.data.EitherT
[error] ^
[error] /Users/edmondoporcu1/Development/credimi/eiric/eiric-api/target/scala-2.12/src_managed/main/swagger/Implicits.scala:7:25: Unused import
[error] import scala.concurrent.Future
[error] ^
```