Available gRPC services:
- Service A: echo.EchoServiceA
- Service B: echo.EchoServiceB

Routing:
- /echo.EchoServiceA/* → Service A
- /echo.EchoServiceB/* → Service B
- /grpc.health.v1.Health/* → Service A (default)

Example gRPC calls:
- grpcurl -H 'path: /echo.EchoServiceA/Echo' ...
- grpcurl -H 'path: /echo.EchoServiceB/Echo' ...