How do I retrieve the updated customfield id when Jira updated IssueEvent is triggered

[Fadli Abdul Rahman]

Inside the method `issueUpdated#IssueEventListener`,
when we call

issueEvent.getChangeLog.getRelated("ChildChangeItem")

it will return a `GenericValue` which consists of the updated field.

For the returned `GenericValue` if the `issuetype` = `jira`, the value of `field` is the `id` of the jira field, but for custom field which the `issuetype` = `custom` the value of `field` is the `name` of the custom field instead of the `id` of the custom field.

Is there any way that I can retrieve the updated custom field id from the `changeLog`?

[Fadli Abdul Rahman]

Moving this discussion to this question instead https://community.atlassian.com/t5/Jira-Software-questions/How-do-I-retrieve-the-updated-customfield-id-when-Jira-updated/qaq-p/1219326