fix wrong code sample in helloworld-go README.md (#5746)

code-samples/eventing/helloworld/helloworld-go/README.md

@@ -34,67 +34,69 @@ cd knative-docs/code-samples/eventing/helloworld/helloworld-go
    code creates a basic web server which listens on port 8080:
 
    ```go
+   package main
+
    import (
-      "context"
-      "log"
-      cloudevents "github.com/cloudevents/sdk-go/v2"
-      "github.com/google/uuid"
+     "context"
+     "log"
+
+     cloudevents "github.com/cloudevents/sdk-go/v2"
+     "github.com/google/uuid"
    )
-
-   func receive(ctx context.Context, event cloudevents.Event)( * cloudevents.Event, cloudevents.Result) {
-      // Here is where your code to process the event will go.
-      // In this example we will log the event msg
-      log.Printf("Event received. \n%s\n", event)
-      data: = & HelloWorld {}
-      if err: = event.DataAs(data);
-      err != nil {
-          log.Printf("Error while extracting cloudevent Data: %s\n", err.Error())
-          return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err)
-      }
-      log.Printf("Hello World Message from received event %q", data.Msg)
-      // Respond with another event (optional)
-      // This is optional and is intended to show how to respond back with another event after processing.
-      // The response will go back into the knative eventing system just like any other event
-      newEvent: = cloudevents.NewEvent()
-      newEvent.SetID(uuid.New().String())
-      newEvent.SetSource("knative/eventing/samples/hello-world")
-      newEvent.SetType("dev.knative.samples.hifromknative")
-      if err: = newEvent.SetData(cloudevents.ApplicationJSON, HiFromKnative {
-          Msg: "Hi from helloworld-go app!"
-      });
-      err != nil {
-          return nil, cloudevents.NewHTTPResult(500, "failed to set response data: %s", err)
-      }
-      log.Printf("Responding with event\n%s\n", newEvent)
-      return &newEvent, nil
+
+   func receive(ctx context.Context, event cloudevents.Event) (*cloudevents.Event, cloudevents.Result) {
+     // Here is where your code to process the event will go.
+     // In this example we will log the event msg
+     log.Printf("Event received. \n%s\n", event)
+     data := &HelloWorld{}
+     if err := event.DataAs(data); err != nil {
+       log.Printf("Error while extracting cloudevent Data: %s\n", err.Error())
+       return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err)
+     }
+     log.Printf("Hello World Message from received event %q", data.Msg)
+
+     // Respond with another event (optional)
+     // This is optional and is intended to show how to respond back with another event after processing.
+     // The response will go back into the knative eventing system just like any other event
+     newEvent := cloudevents.NewEvent()
+     // Setting the ID here is not necessary. When using NewDefaultClient the ID is set
+     // automatically. We set the ID anyway so it appears in the log.
+     newEvent.SetID(uuid.New().String())
+     newEvent.SetSource("knative/eventing/samples/hello-world")
+     newEvent.SetType("dev.knative.samples.hifromknative")
+     if err := newEvent.SetData(cloudevents.ApplicationJSON, HiFromKnative{Msg: "Hi from helloworld-go app!"}); err != nil {
+       return nil, cloudevents.NewHTTPResult(500, "failed to set response data: %s", err)
+     }
+     log.Printf("Responding with event\n%s\n", newEvent)
+     return &newEvent, nil
    }
-
+   
    func main() {
-      log.Print("Hello world sample started.")
-      c, err: = cloudevents.NewDefaultClient()
-      if err != nil {
-        log.Fatalf("failed to create client, %v", err)
-      }
-      log.Fatal(c.StartReceiver(context.Background(), receive))
+     log.Print("Hello world sample started.")
+     c, err := cloudevents.NewDefaultClient()
+     if err != nil {
+       log.Fatalf("failed to create client, %v", err)
+     }
+     log.Fatal(c.StartReceiver(context.Background(), receive))
    }
-    ```
+   ```
 
 1. Create a new file named `eventschemas.go` and paste the following code. This
    defines the data schema of the CloudEvents.
 
    ```go
    package main
-
+   
    // HelloWorld defines the Data of CloudEvent with type=dev.knative.samples.helloworld
    type HelloWorld struct {
-       // Msg holds the message from the event
-       Msg string `json:"msg,omitempty,string"`
+     // Msg holds the message from the event
+     Msg string `json:"msg,omitempty"`
    }
-
+   
    // HiFromKnative defines the Data of CloudEvent with type=dev.knative.samples.hifromknative
    type HiFromKnative struct {
-       // Msg holds the message from the event
-       Msg string `json:"msg,omitempty,string"`
+     // Msg holds the message from the event
+     Msg string `json:"msg,omitempty"`
    }
    ```