curl --request GET \
  --url https://api.hubapi.com/comments/v3/comments/{comment_id}

{
  "id": 409695529,
  "portalId": 62515,
  "contentId": 6860971618,
  "contentTitle": "Test Blog",
  "contentPermalink": "http://demo-hubapi.hs-sites.com/tb-es/test-blog",
  "collectionId": 6513512292,
  "createdAt": 1550182973778,
  "deletedAt": 0,
  "userName": "test testerson",
  "firstName": "test testerson",
  "lastName": "",
  "userEmail": "test@gmail.com",
  "comment": "sample test comment",
  "userUrl": "",
  "state": "APPROVED",
  "userIp": "2601:19b:b00:5fd8:d5de:a9f0:e503:162c",
  "userReferrer": "",
  "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36",
  "contentAuthorEmail": "testapi@hubspot.com",
  "contentAuthorName": "Test 2",
  "contentCreatedAt": 1545651277462,
  "threadId": "0001.0000.0000.0000.0000.0000.0000.0000.0000.0000",
  "replyingTo": null,
  "parentId": 0,
  "legacyId": 0,
  "extraContext": {},
  "parent": null
}