Context properties are not evaluated when using /api/proxy/all

[mikklfr]

Describe the bug

Contextual properties should be evaluated in the same way regardless of the routing /api/proxy/all, /api/proxy or /api/frontend

Steps to reproduce the bug

1. Create a strategy that uses context properties such as the ones defined in the test file with_custom_constraint.json

2. Call the API using /api/proxy/all?properties[companyId]=bricks

3. The strategy will not match the output of /api/frontend?properties[companyId]=bricks or /api/proxy?properties[companyId]=bricks

Expected behavior

Contextual properties from /api/proxy/all should be evaluated in the same way than /api/frontend and /api/proxy.
In that case the flag should be enabled when companyId=bricks

Logs, error output, etc.

No response

Screenshots

No response

Additional context

Client impact

/api/proxy/all is mandatory for Dart SDK users to be able to rely on edge to fetch unleash flags and ensure metrics propagation

How to reproduce the issue usings tests

The test can_handle_custom_context_fields in frontend_api.rs does not check the flag enabled property.
This code allows to see the difference between the different endpoints.

        let req = test::TestRequest::get()
            .uri("/api/frontend?properties[companyId]=bricks")
            .insert_header(ContentType::json())
            .insert_header(("Authorization", auth_key.clone()))
            .to_request();
        let no_escape: FrontendResult = test::call_and_read_body_json(&app, req).await;
        assert!(no_escape.toggles.iter().all(|toggle| toggle.enabled));

        let req = test::TestRequest::get()
            .uri("/api/proxy?properties[companyId]=bricks")
            .insert_header(ContentType::json())
            .insert_header(("Authorization", auth_key.clone()))
            .to_request();
        let no_escape: FrontendResult = test::call_and_read_body_json(&app, req).await;
        assert!(no_escape.toggles.iter().all(|toggle| toggle.enabled));

        let req = test::TestRequest::get()
        .uri("/api/proxy/all?properties[companyId]=bricks")
        .insert_header(ContentType::json())
        .insert_header(("Authorization", auth_key.clone()))
        .to_request();
        let no_escape: FrontendResult = test::call_and_read_body_json(&app, req).await;
        assert!(no_escape.toggles.iter().all(|toggle| toggle.enabled));

Note: The flags are evaluated correctly with the custom properties using POST calls but not on the ones that rely on GET such as the ones from the Flutter / Dart SDK.

Unleash version

v19.5.0

Subscription type

Enterprise

Hosting type

Self-hosted

SDK information (language and version)

curl and Dart SDK

[sighphyre]

Thank you for the most excellent bug report!

We've patched this and released Edge 19.5.1