Retain old username in issue history

Current behaviour:

When a user changes their username, the issue history does not retain its previous username and replaces it with the new one.

Steps to reproduce:

1. Create a user (let's say 'test') and using the user, perform certain actions on any issue (like adding issue links, comments etc)
2. Notice that the issue history tab shows changes made by this user 'test'.
3. Now rename this user from the administration console giving it a new username (say 'testabc').
4. Now make some more changes to the issue using this renamed user.
5. Now go to the history tab and notice that the old username 'test' is replaced by the new username 'testabc'.

Suggestion:

It is important for some customers that Atlassian retains the old usernames of the users in issue history.

Why is this important?

• Confusion as neither Account ID nor Email is shown in the issue history though those are the unique identifiers of a Jira user.
• A non-technical reviewer of the Jira issue may think it to be identity theft
• There is no way to find out about the change because name changes are not reflected in audit logs