makes subscription start from MessageId.latest defaultly

[aloyszhang]

Motivation

Currently , if we did not specify the position when create a new subscription, it's will use the earliest position defaulty. https://github.com/apache/pulsar/blob/master/pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/PersistentTopicsBase.java#L2002
This PR makes subscription start from MessageId.latest defaultly

[sijie]

@aloyszhang the change looks good. Can you add a test case?

[zymap]

Hi @aloyszhang, I think the root cause is that we haven't handled the messageId correctly. I left a comment here #9441 (comment).

[aloyszhang]

@zymap Yes, you're right, I'll check this later and add some test code.

[aloyszhang]

@zymap So far, I didn't find a way to handle a String type parameter like earlist or latest in the broker side. So maybe we have to use specify the messageId like -d '{"ledgerId": 1, "entryId": 1, "partitionIndex": -1}' when using REST API.

Do you have any idea about this?

[aloyszhang]

Since this PR does not resolve issue #9441, so remove the Fixes #9441 information.

[aloyszhang]

/pulsarbot run-failure-checks

[zymap]

@aloyszhang I think there has an easier way is add query params at this API and allow it to pass a message position string. If the user only specifies the message position with a string in the query params, we can use it to create a cursor. Otherwise, we can use the current logic to handle it.

For example, if a request URL likes this:

/tenant/ns/topic/subscription/sub-name?position=latest

We can create a subscription from the latest position

if a request URL likes this:

/tenant/ns/topic/subscription/sub-name?position=latest

body: {ledgerId: 1, entryId: 2, batchIndex: 1}

We can use current logic to handle it.

[aloyszhang]

@zymap Thanks for your suggestions.

if a request URL likes this:
/tenant/ns/topic/subscription/sub-name?position=latest
body: {ledgerId: 1, entryId: 2, batchIndex: 1}

Only one thing need to be figured out, if the request have boths position and ledgerId:entryId:partitionIndex, I think this may make user more confused about the REST API， right?

[aloyszhang]

/pulsarbot run-failure-checks

[sijie]

@zymap Can you review it again?