CORS Support Not Working Properly in Generated Netty Server

[dpacheco-groupieticket]

Description:
The generated Netty server from smithy-java-server-codegen doesn't properly handle CORS requests despite having @cors traits in the Smithy model. While OPTIONS preflight requests work, actual requests (POST/GET) don't include CORS headers in responses.

Current Behavior:

1. OPTIONS preflight requests return correct CORS headers
2. Actual requests (POST/GET) return:
   • Correct status codes (200/201)
   • Correct response bodies
   • But missing Access-Control-Allow-Origin and other CORS headers
3. Browser shows error: "CORS header 'Access-Control-Allow-Origin' missing"

Expected Behavior:
All responses should include CORS headers when:

1. The request contains an Origin header
2. The origin matches the @cors trait configuration
3. For both preflight (OPTIONS) and actual requests

Reproduction Steps:

1. Model with @cors trait:

@cors(origin: "http://localhost:5173")
service MyService {
    operations: [MyOperation]
}

2. Generate Java server code
3. Start server and make CORS request from browser
4. Observe missing headers in actual requests

[dpacheco-groupieticket]

Is there any workaround to make the Netty service respond with the origin CORS header?

[adwsingh]

@dpacheco-groupieticket None that I can think of right now. It shouldn't be too complicated to add support for this, however we are right now focussing on some different aspects of smithy-java so it will take some time before we can address this.

[rhernandez35]

Merged in #756, thank you for the contribution.