diff --git a/src/main/scala/com/wordnik/swagger/codegen/model/LegacySerializers.scala b/src/main/scala/com/wordnik/swagger/codegen/model/LegacySerializers.scala
index d36822ee053..499920ce102 100644
--- a/src/main/scala/com/wordnik/swagger/codegen/model/LegacySerializers.scala
+++ b/src/main/scala/com/wordnik/swagger/codegen/model/LegacySerializers.scala
@@ -201,7 +201,7 @@ object LegacySerializers {
           ""
         }),
         (json \ "nickname").extractOrElse({
-          !!(json, OPERATION, "nickname", "missing required field", ERROR)
+          !!(json, OPERATION, "nickname", "missing required field", WARNING)
           ""
         }),
         (json \ "position").extractOrElse(0),