Sync examples for the Goa v3.31.0 generation upgrade

README.md

@@ -4,11 +4,19 @@
 
 This repository contains examples of microservices implemented using
 [Goa](https://github.com/goadesign/goa). Each example focuses on a specific topic as indicated by
-the directory name. The [cellar](https://github.com/goadesign/examples/tree/master/cellar) example
+the directory name. The [cellar](https://github.com/goadesign/examples/tree/main/cellar) example
 provides a complete implementation of a simple microservice.
-The [retry](https://github.com/goadesign/examples/tree/master/retry) example shows how generated
+The [retry](https://github.com/goadesign/examples/tree/main/retry) example shows how generated
 HTTP and gRPC clients safely retry temporary failures.
 
+The v3.31.0 examples accompany Goa v3.31.0 and require Go 1.26 or later.
+This Goa release includes intentional generated-source and transport changes.
+When adapting an existing application, read the
+[upgrade guide](https://github.com/goadesign/goa/blob/v3.31.0/UPGRADING.md)
+and use matching Goa and examples versions. Regenerate the complete `gen`
+directory and update handwritten interceptors, multipart decoders, and command
+starters as described there.
+
 The samples in each directory serve as templates, and you can clone them using the `gonew` command, as explained in [this blog post](https://go.dev/blog/gonew).
 
 ```shell

basic/gen/goa.json

@@ -1,3 +1,3 @@
 {
-  "goa_version": "v3.30.0"
+  "goa_version": "v3.31.0-preview.5"
 }

basic/gen/grpc/calc/pb/goagen_basic_calc.proto

@@ -19,11 +19,11 @@ service Calc {
 
 message MultiplyRequest {
 	// Left operand
-	sint32 a = 1;
+	optional sint32 a = 1;
 	// Right operand
-	sint32 b = 2;
+	optional sint32 b = 2;
 }
 
 message MultiplyResponse {
-	sint32 field = 1;
+	optional sint32 field = 1;
 }