Circe Encoder Decoder question

CirceEncoderDecoder.scala

import com.twitter.finagle.httpx.Method
import com.twitter.finagle.httpx.path.Path
import cats.data.Xor
import io.circe.Json.JString
import io.circe.{Encoder, _}
import io.circe.jawn._
import io.circe.generic.auto._ 

case class Foo(method: Option[com.twitter.finagle.httpx.Method])

val foo1 = Foo(Some(Method.Get))
val foo2 = Foo(None)

val f1json = foo1.asJson
val f2json = foo2.asJson

implicit val encodeMethod: Encoder[Method] = Encoder[String].contramap(_.toString)
implicit val decodeMethod: Decoder[Method] = Decoder[String].map(Method(_))

val f1EncodeDecode = decode[Foo](f1json.toString)
val f2EncodeDecode = decode[Foo](f2json.toString)