Fix google.protobuf.Any JSON marshaling missing @type field

[Copilot]

google.protobuf.Any types were marshaling to JSON without the required @type field, causing deserialization failures. The deprecated github.com/golang/protobuf/jsonpb package doesn't emit this field per spec.

Changes

Migrated JSON codecs to google.golang.org/protobuf/encoding/protojson:

• codec/json/marshaler.go - Use protojson.MarshalOptions
• codec/json/json.go - Use protojson.Marshal/Unmarshal for proto messages
• server/grpc/codec.go - Use protojson for JSON codec operations

Binary proto codec unchanged:

• codec/proto/* - Retained github.com/golang/protobuf/proto for backward compatibility
• Binary serialization doesn't involve Any type JSON issues

Example

After fix, Any types produce spec-compliant JSON:

anyMsg, _ := anypb.New(wrapperspb.String("test"))
data, _ := json.Marshaler{}.Marshal(anyMsg)
// Before: {"value":"test"}  ❌ missing @type
// After:  {"@type":"type.googleapis.com/google.protobuf.StringValue","value":"test"}  ✓

The @type field enables proper type identification during unmarshaling.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• 224.0.0.251
  • Triggering command: REDACTED, pid is -1 (packet block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[BUG] protoc use google.protobuf.Any error</issue_title>
<issue_description>## Describe the bug

using resp protoc is google.protobuf.Any

error:Any JSON doesn't have '@type'

How to reproduce the bug

Any JSON doesn't have '@type'

Environment

Go Version: 1.24.0

set GOHOSTARCH=amd64
set GOHOSTOS=windows

</issue_description>

<agent_instructions>---
using resp protoc is google.protobuf.Any

error:Any JSON doesn't have '@type'

Is there a fix for this?</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@asim Is there a solution to this?

• Fixes [BUG] protoc use google.protobuf.Any error #2745

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