Hi Pulsar Community, I want to discuss the return value of the `org.apache.pulsar.client.admin.Topics#getMessageById`, which returns `Message<byte[]>`. If the message is a batch message, we only get the first message from the batch message.
So I want to change this behavior by returning `List<Message<byte[]>`, and in the CLI, we also need to print multiple messages when using `get-message-by-id`. Now, I am adding a new method with the same name and a `batchIndex` parameter. When "batchIndex" is -1, we can retrieve all messages from the batch message. Otherwise, we get one message by giving the index. For this implementation, please see https://github.com/apache/pulsar/pull/21813. In long time ago, there was also a PR to fix this issue, please see https://github.com/apache/pulsar/pull/19827. Two PR uses different ways to fix this issue, please let me know your thoughts! Thanks, Zixuan
