Describe the bug
A topic created with a producer in batch mode generates batch messages id : ledgerId:entryId:partitionIndex:batchIndex.
The getLastMessageId method return a MessageIdImpl which doesn't use the batchIndex parameter.

To Reproduce

1. Send messages with a producer in batch mode :
   `

    public class ProducerTest {
   

   public static void main(String[] args) throws Exception {

    try (PulsarClient client = PulsarClient.builder()
    		.serviceUrl("pulsar://localhost:6650")
    		.build()) {
   
    	Producer<String> producer = client
    			.newProducer(Schema.STRING)
    			.topic("topic")
    			.enableBatching(true)
    			.batchingMaxMessages(10)
    			.blockIfQueueFull(false)
    			.batchingMaxPublishDelay(100, TimeUnit.SECONDS)
    			.create();
   
    	CompletableFuture<MessageId> messageIdCompletableFuture = null;
    	for (int i = 0; i < 10; i++) {
    		messageIdCompletableFuture = producer.newMessage()
    				.value(String.valueOf(i))
    				.sendAsync();
    	}
   
    	messageIdCompletableFuture.get();
    }
   

   }
   }`

2. Shows generated messages :

|value|__topic |__messageId |__messageIdToString|
|0 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 00]|39792:0: -1:0 |
|1 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 01]|39792:0: -1:1 |
|2 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 02]|39792:0: -1:2 |
|3 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 03]|39792:0: -1:3 |
|4 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 04]|39792:0: -1:4 |
|5 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 05]|39792:0: -1:5 |
|6 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 06]|39792:0: -1:6 |
|7 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 07]|39792:0: -1:7 |
|8 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 08]|39792:0: -1:8 |
|9 |persistent://public/default/topic|[08 F0 B6 02 10 00 20 09]|39792:0: -1:9 |

3. Retrieve the last message id from pulsar admin and display it :
   39792:0: -1

Expected behavior
It shoud return 39792:0: -1:9

Desktop (please complete the following information):

• OS: Ubuntu 18.04
• Pulsar runs in docker standalone instance