Solve ReactiveMongo playframework scala "No implicit format for reactivemongo.bson.BSONObjectID available."

fix_bsonobjectid_implicit.scala

import play.api.libs.json.{Json, Format}

// If you imported 
import play.modules.reactivemongo.json.BSONFormats.BSONObjectIDFormat
// And still getting No implicit format for reactivemongo.bson.BSONObjectID available. error
// Check that your JSON formatter is typed. Change 
implicit val mongoFormat = Json.format[Category]
// to
implicit val mongoFormat: Format[Category] = Json.format[Category]

// This seem to help scala compiler to find all the implicit types

import reactivemongo.play.json._
import reactivemongo.play.json.collection.JSONCollection
import play.api.libs.json._

implicit val mongoFormat: OFormat[Category] = Json.format[Category]