builderJavaJsonCompatiblePOC.scala

trait JavaJsonizer { def toJson: String }

class SimpleJavaJsonizer extends JavaJsonizer {
  def toJson: String = """{"type":"Int", "pattern":"hello*"}"""
}

case class YourBuilder(underlying: JavaJsonizer, name: Option[String]) {
  def build(newName: String): YourBuilder = copy(name = Some(newName))
}

object YourBuilder {

 implicit def javajsonizer2yourbuilder(javajsonizer: JavaJsonizer): YourBuilder = YourBuilder(javajsonizer, None)
 implicit def yourbuilder2javajsonizer(builder: YourBuilder): JavaJsonizer = builder.underlying

}

// Lets use it

import YourBuilder._

val sser = new SimpleJavaJsonizer

sser.build("hello")

sser.build("hello").toJson
 

case class RangeMapper(@JSON from, @JSON to) extends JavaJsonizer {
def sayHello()
}

val o:RangeMapper = JavaJsonizer.toJson("{}")
o.build("hello")
o.sayHello()