json4s(lift-json)がバグってる件

gistfile1.scala

// "org.json4s" %% "json4s-native" % "3.2.4"

import org.json4s._
import org.json4s.native.Serialization._

case class AAA(a : Option[Long],b : Option[Long],c : Option[Long])

object JsonTest {
  def toJson[Value <: AnyRef](any : Value) : String = {
    write(any)(DefaultFormats)
  }
}

/*
scala> JsonTest.toJson(AAA(Some(1),Some(2),Some(3)))
res0: String = {"a":1,"b":2,"c":3}

scala> JsonTest.toJson(AAA(Some(1),Some(2),None))
res1: String = {"a":1,"b":2}

scala> JsonTest.toJson(AAA(Some(1),None,Some(3)))
res2: String = {"a":1,"c":3}

scala> JsonTest.toJson(AAA(None,Some(2),Some(3)))
res3: String = {,"b":2,"c":3} // <- wrong format
 */