lift json serializing mixed type array

MixedTypeArrayJsonSuite.scala

package net.liftweb.sandbox

import org.scalatest.FunSuite
import net.liftweb.json._
import org.scalatest.matchers.ShouldMatchers

/**
 * @author IL
 * @see <a href="https://groups.google.com/forum/?fromgroups#!topic/liftweb/GK5DbzCtWdA">forum</a>
 */
class MixedTypeArrayJsonSuite extends FunSuite with ShouldMatchers {
  implicit val formats = DefaultFormats + new CustomSerializer[Either[String, Entry]](
    format => ( {
      case JString(s) => Left(s)
      case j => Right(j.extract[Entry](DefaultFormats, manifest[Entry]))
    }, {
      case Left(s: String) => JString(s)
      case Right(e: Entry) => Extraction.decompose(e)(DefaultFormats)
    }
      )
  )

  test("extract mixed type list") {
    val a = parse( """{
    "field1": true,
    "field2": "hi",
    "entries": [
        [
            "blah",
            {
                "fielda": 70615911,
                "fieldb": "4358367001dfbd6",
            }
        ],
        [
            "hello.txt",
            {
                "fielda": 363696459,
                "fieldb": "15ad914b001dfbd6",
            }
        ]
   ]
}""")

    val obj = a.extract[Root]

    obj should be === Root(true, "hi",
      (Left("blah") :: Right(Entry(70615911, "4358367001dfbd6")) :: Nil) ::
        (Left("hello.txt") :: Right(Entry(363696459, "15ad914b001dfbd6")) :: Nil) :: Nil)
  }
}

case class Root(field1: Boolean, field2: String, entries: List[List[Either[String, Entry]]])

case class Entry(fielda: Int, fieldb: String)