fix: sttp4 json4s JsonSupport uses sealed trait serializers instead of Enumeration-based EnumNameSerializer

The json4s variant of JsonSupport.scala used EnumNameSerializer which
expects Scala Enumeration types, but sttp4 model templates generate
sealed traits with case objects for enums. This caused compilation
errors since the types are incompatible.

Replace EnumNameSerializer with direct references to the implicit
Serializer objects already defined in each enum's companion object.

Author: plaflamme

modules/openapi-generator/src/main/resources/scala-sttp4/jsonSupport.mustache

@@ -7,34 +7,11 @@ import {{modelPackage}}._
 {{#json4s}}
 import org.json4s._
 import sttp.client4.json4s.SttpJson4sApi
-import scala.reflect.ClassTag
 
 object JsonSupport extends SttpJson4sApi {
   def enumSerializers: Seq[Serializer[_]] = Seq[Serializer[_]](){{#models}}{{#model}}{{#isEnum}} :+
-    new EnumNameSerializer({{classname}}){{/isEnum}}{{#hasEnums}}{{#vars}}{{#isEnum}} :+
-    new EnumNameSerializer({{classname}}Enums.{{datatypeWithEnum}}){{/isEnum}}{{/vars}}{{/hasEnums}}{{/model}}{{/models}}
-
-  private class EnumNameSerializer[E <: Enumeration: ClassTag](enumeration: E) extends Serializer[E#Value] {
-    import JsonDSL._
-    val EnumerationClass: Class[E#Value] = classOf[E#Value]
-
-    def deserialize(implicit format: Formats): PartialFunction[(TypeInfo, JValue), E#Value] = {
-      case (t @ TypeInfo(EnumerationClass, _), json) if isValid(json) =>
-        json match {
-          case JString(value) => enumeration.withName(value)
-          case value => throw new MappingException(s"Can't convert $value to $EnumerationClass")
-        }
-    }
-
-    private[this] def isValid(json: JValue) = json match {
-      case JString(value) if enumeration.values.exists(_.toString == value) => true
-      case _ => false
-    }
-
-    def serialize(implicit format: Formats): PartialFunction[Any, JValue] = {
-      case i: E#Value => i.toString
-      }
-    }
+    {{classname}}.{{classname}}Serializer{{/isEnum}}{{#hasEnums}}{{#vars}}{{#isEnum}} :+
+    {{classname}}Enums.{{datatypeWithEnum}}.{{datatypeWithEnum}}Serializer{{/isEnum}}{{/vars}}{{/hasEnums}}{{/model}}{{/models}}
 
   implicit val format: Formats = DefaultFormats ++ enumSerializers ++ DateSerializers.all ++ AdditionalTypeSerializers.all
   implicit val serialization: org.json4s.Serialization = org.json4s.jackson.Serialization

samples/client/petstore/scala-sttp4/src/main/scala/org/openapitools/client/core/JsonSupport.scala

@@ -14,34 +14,11 @@ package org.openapitools.client.core
 import org.openapitools.client.model._
 import org.json4s._
 import sttp.client4.json4s.SttpJson4sApi
-import scala.reflect.ClassTag
 
 object JsonSupport extends SttpJson4sApi {
   def enumSerializers: Seq[Serializer[_]] = Seq[Serializer[_]]() :+
-    new EnumNameSerializer(OrderEnums.Status) :+
-    new EnumNameSerializer(PetEnums.Status)
-
-  private class EnumNameSerializer[E <: Enumeration: ClassTag](enumeration: E) extends Serializer[E#Value] {
-    import JsonDSL._
-    val EnumerationClass: Class[E#Value] = classOf[E#Value]
-
-    def deserialize(implicit format: Formats): PartialFunction[(TypeInfo, JValue), E#Value] = {
-      case (t @ TypeInfo(EnumerationClass, _), json) if isValid(json) =>
-        json match {
-          case JString(value) => enumeration.withName(value)
-          case value => throw new MappingException(s"Can't convert $value to $EnumerationClass")
-        }
-    }
-
-    private[this] def isValid(json: JValue) = json match {
-      case JString(value) if enumeration.values.exists(_.toString == value) => true
-      case _ => false
-    }
-
-    def serialize(implicit format: Formats): PartialFunction[Any, JValue] = {
-      case i: E#Value => i.toString
-      }
-    }
+    OrderEnums.Status.StatusSerializer :+
+    PetEnums.Status.StatusSerializer
 
   implicit val format: Formats = DefaultFormats ++ enumSerializers ++ DateSerializers.all ++ AdditionalTypeSerializers.all
   implicit val serialization: org.json4s.Serialization = org.json4s.jackson.Serialization