Add binary (Bytes) response support to Spring integration

[nsmnds]

Summary

• Parser: Infer application/octet-stream content type when the body type is Bytes (instead of hardcoded application/json)
• Jackson serialization: Add ByteArray/byte[] passthrough in both Kotlin and Java WirespecSerialization so binary data skips JSON encoding
• Spring ResponseBodyAdvice: Handle binary responses by writing directly to the output stream with Content-Type: application/octet-stream, instead of wrapping in RawJsonBody
• Bug fix: Fix concatGenerics() in Utils.kt to handle Java array bracket notation (byte[] → byte instead of invalid byte[] in interface names)

This enables defining endpoints like:

endpoint DownloadReport GET /api/report -> {
    200 -> Bytes
}

Test plan

• Parser tests: verify Bytes body infers application/octet-stream content type for both request and response
• Spring Kotlin emitter test: verify generated code includes correct handler interface
• Spring Java emitter test: verify generated code includes correct handler interface
• Kotlin Spring integration test: verify binary response returns correct bytes via MockMvc
• Java Spring integration test: verify binary response returns correct bytes via MockMvc
• Existing CRUD, query parameter, and multipart tests still pass

https://claude.ai/code/session_01JNutdTfvBVFQXNDPx9Xb7H

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud