empty Uri fragment ignored

The Uri.withFragment function does not allow one to set an empty fragment, which is allowed by the IETF spec I believe, and by the Uri constructor, as shown:

import akka.http.scaladsl.model.Uri
import Uri.*

scala> val good = Uri("https",Authority(Host("example.com")),Path./("doc"),None,Some(""))       
val good: akka.http.scaladsl.model.Uri = https://example.com/doc#

scala> val noFrag = Uri("https",Authority(Host("example.com")),Path./("doc"),None,None)
val noFrag: akka.http.scaladsl.model.Uri = https://example.com/doc

scala> noFrag.withFragment("")
val res3: akka.http.scaladsl.model.Uri = https://example.com/doc