Response returns 404 instead of 405

[imor]

One of our tests started failing when we upgraded from 1.3.48 to 1.3.52. The test expected that calling a URL with an HTTP method which was not defined for a URL returns status code 405. After the upgrade, status code 404 was returned. I have traced the change in behaviour down to this commit. I also have a minimal example reproducing the problem:

use poem::{listener::TcpListener, Route, Server};
use poem_openapi::{param::Query, payload::PlainText, OpenApi, OpenApiService};

struct Api;

#[OpenApi]
impl Api {
    #[oai(path = "/hello", method = "get")]
    async fn get_hello(&self) -> PlainText<String> {
        PlainText("GET /hello response".to_string())
    }

    #[oai(path = "/hello", method = "delete")]
    async fn delete_hello(&self) -> PlainText<String> {
        PlainText("DELETE /hello response".to_string())
    }

    #[oai(path = "/goodbye", method = "get")]
    async fn get_goodbye(&self) -> PlainText<String> {
        PlainText("GET goodbye response".to_string())
    }
}

#[tokio::main]
async fn main() -> Result<(), std::io::Error> {
    if std::env::var_os("RUST_LOG").is_none() {
        std::env::set_var("RUST_LOG", "poem=debug");
    }
    tracing_subscriber::fmt::init();

    let api_service =
        OpenApiService::new(Api, "Hello World", "1.0").server("http://localhost:3000/api");
    let ui = api_service.swagger_ui();

    Server::new(TcpListener::bind("127.0.0.1:3000"))
        .run(Route::new().nest("/api", api_service).nest("/", ui))
        .await
}

Expected Behavior

Calling DELETE /goodbye should return 405.

Note that if I comment out the delete_hello method, I start getting 405.

Actual Behavior

Calling DELETE /goodbye returns 404.

Steps to Reproduce the Problem

1. Run the above code snippet.
2. Call DELETE /goodbye from browser or from any other HTTP client.
3. Observe that you get a 404 status code instead of a 405.

Specifications

• Version: 1.3.52
• Platform: stable-aarch64-apple-darwin
• Subsystem: