Custom Authentication Scheme Issue

[moconn68]

Description

When creating a custom authentication workflow via the orchestrator using a RuntimePlugin per this discussion post, the authentication plugin is overwritten by the model default. In my case this default is no auth, so the authentication token headers were never used and my requests were rejected from the server. I am able to work around this using an Interceptor per this snippet, but per office hours discussion this is not the idiomatic way and the issue with RutimePlugins should be resolved.

Context

Reproduction

• Create some simple authentication middleware via RuntimePlugin per the discussion post linked above
• Using the following test, evaluate the trace logs and examine the authentication workflow and the final (lack of) headers:

    struct TestEndpointResolver;

    impl<T> ResolveEndpoint<T> for TestEndpointResolver {
        fn resolve_endpoint(&self, _params: &T) -> aws_smithy_http::endpoint::Result {
            Ok(::aws_smithy_types::endpoint::Endpoint::builder()
                .url(ENDPOINT_URL_STR)
                .property(
                    "authSchemes",
                    vec![::aws_smithy_types::Document::from({
                        let mut out = ::std::collections::HashMap::<
                            String,
                            ::aws_smithy_types::Document,
                        >::new();
                        out.insert("name".to_string(), "schemeid".to_string().into());
                        out
                    })],
                )
                .build())
        }
    }
    #[tokio::test]
    async fn proxy_test() {
        tracing_subscriber::fmt::init();
        let (server, request) = capture_request(None);
        let config = Config::builder()
            .http_connector(server)
            .endpoint_resolver(TestEndpointResolver {})
            .runtime_plugin(super::AuthRuntimePlugin::new())
            .build();
        let client = Client::from_conf(config);

        let _ = dbg!(client.get_client_configuration().send().await);
        let r = request.expect_request();
        dbg!(&r);
        assert!(r.headers().is_empty());
    }

Run with RUST_LOGS=trace cargo test proxy_test

Smithy version

v0.56.1

Relevant modifications

N/A

Environment/Deployment Peculiarities

Code running on a custom embedded Linux-based stack