ScalaObjectMapper serializes twice

[mosesn]

We just moved from jackson 2.11.4 to 2.13.0, and we found a performance bug. It seems like ScalaObjectMapper is calling the serialize method twice. We'd like to switch to ClassTagExtensions, but we depend heavily on ScalaObjectMapper, and want to be on a stable version that has both ScalaObjectMapper as well as ClassTagExtensions before we migrate.

Can you please fix this regression in a patch release?

Reproduction case:

import com.fasterxml.jackson.core.JsonGenerator
import com.fasterxml.jackson.databind.JsonNode
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.SerializerProvider
import com.fasterxml.jackson.databind.module.SimpleModule
import com.fasterxml.jackson.databind.ser.std.StdSerializer
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import com.fasterxml.jackson.module.scala.ScalaObjectMapper
import org.scalatest.funsuite.AnyFunSuite
import org.scalatest.matchers.should.Matchers
import org.scalatestplus.scalacheck.Checkers
import org.scalatestplus.scalacheck.ScalaCheckDrivenPropertyChecks

final case class DerpWrapper(derps: Seq[Derp])

final case class Derp(var one: Long) {
  var serializationCounter = 0
}

class JacksonUpgradeTest
    extends AnyFunSuite
    with ScalaCheckDrivenPropertyChecks
    with Checkers
    with Matchers {

  private object DerpModule extends SimpleModule {
    private object DerpResponseSerializer extends StdSerializer[Derp](classOf[Derp]) {
      override def serialize(
        value: Derp,
        gen: JsonGenerator,
        provider: SerializerProvider
      ): Unit = {
        value.serializationCounter = value.serializationCounter + 1
      }
    }
    addSerializer(DerpResponseSerializer)
  }

  val mapper: ObjectMapper with ScalaObjectMapper = {
    val m = new ObjectMapper with ScalaObjectMapper
    m.registerModule(DefaultScalaModule)
      .registerModule(DerpModule)
    m
  }

  test("jackson test") {
    val derps = DerpWrapper(Seq(Derp(1)))
    mapper.valueToTree[JsonNode](derps)
    // the serializer should only be called once, but is getting called twice
    derps.derps.head.serializationCounter should equal(1)
  }
}

[mosesn]

Actually, looks like this might be a databind issue, not module-scala. FasterXML/jackson-databind#3308 seems to be the root cause!

[mosesn]

Closing for now, will reopen if we're mistaken. Sorry for the noise!