Usernames with capital letters disable 'Basic' search

Symptom

"Basic" search button not available in issue navigator where JQL query contains a username with capital letters.

Steps to reproduce

1. Create an user with capital letter(s) in name (e.g. Testuser)
2. Browse to the issue navigator and search for this user either in the "reporter" or "assignee" field
3. You will be able to search either in Basic or Advanced mode
4. In the issue navigator using Advanced mode, search for the user either in the "reporter" or "assignee" field
5. The "Basic" search will be disabled
6. If you hove on the "Basic" link, the message "This query is too complex to display in Simple mode" will be shown

Expected behavior

Be able to search in Basic and Advanced mode

Current behavior

Basic search is disabled.

Workaround

In the JQL make the capital letters lowercase in the username (e.g. testuser)

Additional information

• This behavior is not consistent. In some cases, using the username in its lower case letters work, but that is not always true. Below, there are some examples of usernames where the workaround did work and some other examples where it did not work

  Username	Lower case username	Test Result
  TEST	test	Basic button was displayed
  testUSER	testuser	Basic button was displayed
  Test user	test user	Basic button was displayed
  testing User	testing user	Basic button was still not displayed
  User Test	user test	Basic button was still not displayed