Using Play's MVC RequestHeader info in a WS Client filter

MyWsClient.java

import javax.inject.{Inject, Singleton}

import play.api.libs.ws.{WSClient, WSRequest, WSRequestFilter}

@Singleton
class MyWsClient @Inject()(wsClient: WSClient,
                           filters: java.util.Set[WSRequestFilter] ) extends WSClient {

  override def underlying[T]: T = wsClient.asInstanceOf[T]

  override def url (url: String): WSRequest = {
    val request: WSRequest = wsClient.url(url)
    filters.forEach(filter => request.withRequestFilter(filter))
    request
  }

  override def close (): Unit = wsClient.close ()
}

TracerForwarderWsClientFilter.scala

@Singleton
class TracerForwarderWsClientFilter @Inject()(configuration: Config)
                                             (implicit parentRequest: RequestHeader) extends WSRequestFilter {
  
  val someValue = configuration.getInt("foobar")
  
  override def apply(executor: WSRequestExecutor): WSRequestExecutor = {
    (request: StandaloneWSRequest) => {
      request.addHttpHeaders(("x-tracer-id", parentRequest.headers.get("x-tracer-id").getOrElse("n/a")))
      executor.apply(request)
    }
  }
}

WsClientFiltersModule.scala

import com.google.inject.AbstractModule
import com.google.inject.multibindings.Multibinder
import play.api.libs.ws.WSRequestFilter

class WsClientFiltersModule extends AbstractModule {
  override protected def configure(): Unit = {
    val requestFilterMultibinder: Multibinder[WSRequestFilter] = Multibinder.newSetBinder(binder, classOf[WSRequestFilter])
    requestFilterMultibinder.addBinding().to(classOf[TracerForwarderWsClientFilter]).asEagerSingleton()
  }
}