Merge pull request #512 from cchantep/fix/sub-trait

play-json/shared/src/main/scala/play/api/libs/json/JsMacroImpl.scala

@@ -676,7 +676,7 @@ class JsMacroImpl(val c: blackbox.Context) {
               case jsv => $json.JsObject(Seq("_value" -> jsv))
             }
 
-            jso + ($config.discriminator -> $json.JsString($config.typeNaming(${t.typeSymbol.fullName})))
+            $json.JsObject(Map($config.discriminator -> $json.JsString($config.typeNaming(${t.typeSymbol.fullName})))) ++ jso
           }"""
           }
         )

play-json/shared/src/test/scala/play/api/libs/json/MacroSpec.scala

@@ -144,6 +144,14 @@ class MacroSpec extends AnyWordSpec with Matchers with org.scalatestplus.scalach
         jsSimple.validate[Family].mustEqual(JsSuccess(simple))
         jsOptional.validate[Family].mustEqual(JsSuccess(optional))
       }
+
+      "subtype is a sealed trait itself" in {
+        val expected   = Leaf2(1)
+        val expectedJs = Json.obj("_type" -> "play.api.libs.json.MacroSpec.Leaf2", "value" -> 1)
+
+        Json.toJson[TreeValue](expected) mustEqual expectedJs
+        expectedJs.validate[TreeValue] mustEqual JsSuccess(expected)
+      }
     }
 
     "be generated for a ValueClass" in {
@@ -666,6 +674,21 @@ class MacroSpec extends AnyWordSpec with Matchers with org.scalatestplus.scalach
    */
   }
 
+  sealed trait TreeValue
+
+  sealed trait SubLevel extends TreeValue
+
+  case class Leaf1(value: String) extends TreeValue
+  case class Leaf2(value: Int)    extends SubLevel
+
+  object TreeValue {
+    private implicit val leaf1: OFormat[Leaf1]       = Json.format
+    private implicit val leaf2: OFormat[Leaf2]       = Json.format
+    private implicit val subLevel: OFormat[SubLevel] = Json.format
+
+    implicit val format: OFormat[TreeValue] = Json.format
+  }
+
   object Foo {
     import shapeless.tag.@@