Compatible the HTTP header properties with PIP-279 (#1299)

### Motivation

After [pip-279](apache/pulsar#20627), all properties keys and values use json string save to header: `X-Pulsar-Property`

This PR to compatible with this change when using subscription admin API.

Also, Using `pip-279` also avoids the issue where the Go HTTP client automatically formats HTTP headers: golang/go#37834, This will impact the peek command, the previous method might retrieve `properties` with inconsistent casing compared to the user-defined.

### Modifications
- Compatible the HTTP header properties with PIP-279

Author: shibd

pulsaradmin/pkg/admin/subscription.go

@@ -20,6 +20,7 @@ package admin
 import (
 	"bytes"
 	"encoding/binary"
+	"encoding/json"
 	"io"
 	"net/http"
 	"net/url"
@@ -230,7 +231,14 @@ func safeRespClose(resp *http.Response) {
 const (
 	PublishTimeHeader = "X-Pulsar-Publish-Time"
 	BatchHeader       = "X-Pulsar-Num-Batch-Message"
-	PropertyPrefix    = "X-Pulsar-Property-"
+
+	// PropertyPrefix is part of the old protocol for message properties.
+	PropertyPrefix = "X-Pulsar-Property-"
+
+	// PropertyHeader is part of the new protocol introduced in SNIP-279
+	// https://github.com/apache/pulsar/pull/20627
+	// The value is a JSON string representing the properties.
+	PropertyHeader = "X-Pulsar-Property"
 )
 
 func handleResp(topic utils.TopicName, resp *http.Response) ([]*utils.Message, error) {
@@ -261,6 +269,11 @@ func handleResp(topic utils.TopicName, resp *http.Response) ([]*utils.Message, e
 				properties[BatchHeader] = h
 			}
 			return getIndividualMsgsFromBatch(topic, ID, payload, properties)
+		case k == PropertyHeader:
+			propJSON := resp.Header.Get(k)
+			if err := json.Unmarshal([]byte(propJSON), &properties); err != nil {
+				return nil, err
+			}
 		case strings.Contains(k, PropertyPrefix):
 			key := strings.TrimPrefix(k, PropertyPrefix)
 			properties[key] = resp.Header.Get(k)

pulsaradmin/pkg/admin/subscription_test.go

@@ -144,6 +144,58 @@ func TestPeekMessageForPartitionedTopic(t *testing.T) {
 	}
 }
 
+func TestPeekMessageWithProperties(t *testing.T) {
+	randomName := newTopicName()
+	topic := "persistent://public/default/" + randomName
+	topicName, _ := utils.GetTopicName(topic)
+	subName := "test-sub"
+
+	cfg := &config.Config{}
+	admin, err := New(cfg)
+	assert.NoError(t, err)
+	assert.NotNil(t, admin)
+
+	client, err := pulsar.NewClient(pulsar.ClientOptions{
+		URL: lookupURL,
+	})
+	assert.NoError(t, err)
+	defer client.Close()
+
+	// Create a producer for non-batch messages
+	producer, err := client.CreateProducer(pulsar.ProducerOptions{
+		Topic:           topic,
+		DisableBatching: true,
+	})
+	assert.NoError(t, err)
+	defer producer.Close()
+
+	props := map[string]string{
+		"key1":        "value1",
+		"KEY2":        "VALUE2",
+		"KeY3":        "VaLuE3",
+		"details=man": "good at playing basketball",
+	}
+
+	_, err = producer.Send(context.Background(), &pulsar.ProducerMessage{
+		Payload:    []byte("test-message"),
+		Properties: props,
+	})
+	assert.NoError(t, err)
+
+	// Peek messages
+	messages, err := admin.Subscriptions().PeekMessages(*topicName, subName, 1)
+	assert.NoError(t, err)
+	assert.NotNil(t, messages)
+
+	// Verify properties of messages
+	for _, msg := range messages {
+		assert.Equal(t, "value1", msg.Properties["key1"])
+		assert.Equal(t, "VALUE2", msg.Properties["KEY2"])
+		assert.Equal(t, "VaLuE3", msg.Properties["KeY3"])
+		assert.Equal(t, "good at playing basketball", msg.Properties["details=man"])
+	}
+}
+
 func TestGetMessageByID(t *testing.T) {
 	randomName := newTopicName()
 	topic := "persistent://public/default/" + randomName