ASB: Add support for ApplicationProperties in subscriptions (#3436)

Signed-off-by: Bernd Verst <github@bernd.dev>

common/component/azure/servicebus/message_pubsub.go

@@ -15,6 +15,7 @@ package servicebus
 
 import (
 	"encoding/base64"
+	"github.com/spf13/cast"
 	"net/http"
 	"strconv"
 
@@ -58,6 +59,12 @@ func addMessageAttributesToMetadata(metadata map[string]string, asbMsg *azservic
 		metadata = map[string]string{}
 	}
 
+	for key, val := range asbMsg.ApplicationProperties {
+		metadata["metadata."+key] = cast.ToString(val)
+	}
+
+	// We are not concerned about key conflicts here as we do not allow custom properties that match well-known property names
+
 	if asbMsg.MessageID != "" {
 		metadata["metadata."+MessageKeyMessageID] = asbMsg.MessageID
 	}

common/component/azure/servicebus/message_pubsub_test.go

@@ -44,6 +44,10 @@ func TestAddMessageAttributesToMetadata(t *testing.T) {
 				ScheduledEnqueueTime: &testSampleTime,
 				PartitionKey:         &testPartitionKey,
 				LockedUntil:          &testSampleTime,
+				ApplicationProperties: map[string]interface{}{
+					"hello":   "world",
+					"numeric": 1,
+				},
 			},
 			expectedMetadata: map[string]string{
 				"metadata." + MessageKeyMessageID:               testMessageID,
@@ -60,6 +64,8 @@ func TestAddMessageAttributesToMetadata(t *testing.T) {
 				"metadata." + MessageKeyScheduledEnqueueTimeUtc: testSampleTimeHTTPFormat,
 				"metadata." + MessageKeyPartitionKey:            testPartitionKey,
 				"metadata." + MessageKeyLockedUntilUtc:          testSampleTimeHTTPFormat,
+				"metadata.hello":                                "world",
+				"metadata.numeric":                              "1",
 			},
 		},
 	}