Afterburner Interferes With Options Respecting Include.NON_NULL

[omervk]

If Afterburner (jackson-module-afterburner) is registered on an ObjectMapper before DefaultScalaModule, it interferes with (at least) how None is serialized when Include.NON_NULL is in play.

case class A(foo: Option[String] = None)
class B {
    @JsonProperty val foo: Option[String] = None
}

val objectMapper = new ObjectMapper()
objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL)
objectMapper.registerModule(new AfterburnerModule)
objectMapper.registerModule(DefaultScalaModule)

val caseClassJson = objectMapper.writeValueAsString(A())
val objectJson = objectMapper.writeValueAsString(new B())
val anonymousObjectJson = objectMapper.writeValueAsString(new {
    @JsonProperty val foo: Option[String] = None
})

Expected:

caseClassJson == "{}"
objectJson == "{}"
anonymousObjectJson == "{}"

Actual:

caseClassJson == """{ "foo": null }"""
objectJson == """{ "foo": null }"""
anonymousObjectJson == "{}"

[christophercurrie]

Interesting. Does the order of registering the modules make a difference?

[cowtowncoder]

Another thing that may be of importance here is that Jackson 2.6 has improved support for "referential" types, aimed at better support for Option/Optionals (and some other similar types like AtomicReference).
There are things module needs to do to take advantage of this, we may need to verify that Scala module does those. This matters mostly because jackson-databind is responsible for much/most of actual serialization exclusion handling.

@christophercurrie JDK8 module and Guava have relevant code, and maybe former is simpler example, on how to resolve option(al) type as ReferenceType, if that is not yet done (I forget whether we talked about this earlier)

[christophercurrie]

I don't think that the Scala module has yet picked up on that. I'll dig into the JDK8 module's examples as time allows.

[omervk]

@christophercurrie

Interesting. Does the order of registering the modules make a difference?

Yes, registering Afterburner after the Scala module does not cause this issue. I am not sure whether it might cause issues with Afterburner, though.

[omervk]

As a side-effect of the 2.7.4 release, the non-standard NON_NULL behavior with respect to Option has been fixed and the correct NON_ABSENT should be used instead. Original issue has also been resolved.

Thanks 👍

[cowtowncoder]

@omervk Thank you for verifying this.