How can I determine the parent item of a lock event?

Given a lock event returned from the List user and enterprise events endpoint, how can I determine the parent item that the event applies to? I cannot see any reference to the parent from the response payload (see below) nor any “Get lock by ID” endpoint or equivalent that I could use.

Lock event response example

{
  "type" : "event",
  "createdAt" : "2026-03-19T14:41:22Z",
  "recordedAt" : "2026-03-19T14:41:25Z",
  "eventId" : "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
  "createdBy" : {
    "id" : "XXXXXXXXXXX",
    "type" : "USER",
    "name" : "Foo Bar",
    "login" : "foo.bar@example.com"
  },
  "eventType" : "LOCK_CREATE",
  "source" : {
    "id" : "XXXXXXXXXXX",
    "type" : "LOCK",
    "createdAt" : {
      "value" : "2026-03-19T14:41:22Z",
      "isPresent" : true
    },
    "modifiedAt" : {
      "isPresent" : false
    },
    "notificationEmail" : {
      "isPresent" : false
    },
    "parent" : {
      "isPresent" : false
    },
    "etag" : {
      "isPresent" : false
    },
    "sequenceId" : {
      "isPresent" : false
    },
    "trashedAt" : {
      "isPresent" : false
    },
    "purgedAt" : {
      "isPresent" : false
    },
    "contentCreatedAt" : {
      "isPresent" : false
    },
    "contentModifiedAt" : {
      "isPresent" : false
    },
    "createdBy" : {
      "id" : "XXXXXXXXXXX",
      "type" : "USER",
      "name" : "Foo Bar",
      "login" : "foo.bar@example.com"
    },
    "sharedLink" : {
      "isPresent" : false
    },
    "folderUploadEmail" : {
      "isPresent" : false
    }
  },
  "additionalDetails" : { }
}