Rack Instrumentation - How to start new parent span for public endpoints?

[hwu-roadie]

For some endpoints with a public ingress there may be a traceparent header on the incoming request, but the request's parent trace originates from somewhere that will never be ingested in the receiving system. The result for the receiving system is that when they store their trace in a backend the parent trace will never be found so the parent trace name could be ambiguous or other effects depending on the backend.

As a reference to another language SDK, Go's otelhttp package has a WithPublicEndpointFn option that has the following in the docs:

WithPublicEndpointFn runs with every request, and allows conditionally configuring the Handler to link the span with an incoming span context. If this option is not provided or returns false, then the association is a child association instead of a link.

Is there a similar configuration in the Rack instrumentation or is there another recommendation to start a new parent trace with a link to the incoming span context for certain requests?