Why are newline matchers not allowed in custom rules?

Security for Jira Cloud scans line-by-line, so newline matchers will never be matched. Existing rules which contain newlines will continue to run, but cannot be edited without removing the newline characters.

List of disallowed sequences:

• \n, \x0a, \x0A, \u000a, \u000A

• \r, \x0d, \x0D, \u000d, \u000D

• \R