How do I query X-ray using a http URL, where that URL is not the first part of the request?

Hello.

Suppose that I have the following architecture:

API Gateway (service name: gateway api) -> Lambda Function (service name: gateway handler) -> API Gateway (service name: internal service) -> Lambda Function (service name: internal service handler)

The "internal service" api gateway has 2 endpoints (POST /endpointA and POST /endpointX), which both proxy to the same "handler" lambda function. Depending on a feature flag, incoming requests are requests to the "gateway handler" are sent to either POST /endpointA or POST /endpointX. All of these services are set up for tracing with AWS X-ray.

I want to query X-Ray to gain insights into the performance of requests send to X vs A.

I tried the following query

service("gateway handler") AND service("internal service") AND http.url ENDSWITH "/endpointX"
// and also //
service("gateway handler") AND service("internal service") AND http.url ENDSWITH "/endpointA"

However this does not seem to work. In general I cannot query using http.url, when that http request is not the first request in a trace.

Is there a way around this? Bonus points if it does not require me to add additional code to annotate traces for the xray system.