[pulsar-admin] Print topic internal info as formatted json

[yuruguo]

Motivation

Currently, we can get topic internal info through CLI bin/pulsar-admin topics info-internal tn1/ns1/tp1, but I find that what we get is an unformatted and unreadable result, as below:

"{\"version\":0,\"partitions\":{\"persistent://pulsar/application-f75e774c-7e1e-405a-aa57-bfee90b93923/topic-partition-0\":{\"version\":0,\"creationDate\":\"2021-11-10T12:17:01.397+08:00\",\"modificationDate\":\"2021-11-10T12:17:01.397+08:00\",\"ledgers\":[],\"cursors\":{}},\"persistent://pulsar/application-f75e774c-7e1e-405a-aa57-bfee90b93923/topic-partition-1\":{\"version\":0,\"creationDate\":\"2021-11-10T12:17:01.414+08:00\",\"modificationDate\":\"2021-11-10T12:17:01.414+08:00\",\"ledgers\":[],\"cursors\":{}}}}"

The purpose of this PR is to format topic internal info to make it clear and readable, as below:

{
  "version": 0,
  "partitions": {
    "persistent://pulsar/application-f75e774c-7e1e-405a-aa57-bfee90b93923/topic-partition-0": {
      "version": 0,
      "creationDate": "2021-11-10T12:17:01.397+08:00",
      "modificationDate": "2021-11-10T12:17:01.397+08:00",
      "ledgers": [],
      "cursors": {}
    },
    "persistent://pulsar/application-f75e774c-7e1e-405a-aa57-bfee90b93923/topic-partition-1": {
      "version": 0,
      "creationDate": "2021-11-10T12:17:01.414+08:00",
      "modificationDate": "2021-11-10T12:17:01.414+08:00",
      "ledgers": [],
      "cursors": {}
    }
  }
}

Documentation

• no-need-doc

[michaeljmarshall]

LGTM