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`?