WebBrokerAPI: Guard against duplicate listeners in mixed static + xDS deployments (runtime.go)

Summary

In event-gateway/gateway-runtime/internal/runtime/runtime.go, the Run() method's xDS branch unconditionally calls newManagedServer() for WebSocket and WebSub servers, even when LoadChannels() has already appended servers for those protocols/ports to r.servers. In a mixed static + xDS deployment, the second listener bind attempt will fail on the same port while the runtime still proceeds to mark itself ready.

Expected Behavior

Before creating a new server in the xDS block, the runtime should check r.servers for an existing server matching the protocol/port (e.g., WebSocket → r.cfg.Server.WebSocketPort with r.wsMux, WebSub-HTTP → r.cfg.Server.WebSubHTTPPort with r.websubMux, WebSub-HTTPS → r.cfg.Server.WebSubHTTPSPort). If one already exists, reuse it and skip creating a duplicate. Only call newManagedServer() and append/run a new server when no existing server for that protocol/port is registered.

Relevant Code

File: event-gateway/gateway-runtime/internal/runtime/runtime.go
Approximate lines: 445–487 (xDS server startup block in Run())

References

• PR: https://github.com/wso2/api-platform/pull/1954
• Review comment: https://github.com/wso2/api-platform/pull/1954#discussion_r3239562647
• Related PR: https://github.com/wso2/api-platform/pull/1944

Reported by @senthuran16