As described on Using Smart Commits in Bitbucket Server:
Smart Commits only support the default JIRA Software issue key format (that is, two or more uppercase letters, followed by a hyphen and the issue number, for example
Make that configurable. Bitbucket Server allows the rendering non-default JIRA issue keys if that is configured via a JVM argument, for example. See:
There is no workaround for that.
Because JIRA allows custom issue keys so we should support it across the board.