I'm afraid this is currently not possible - the only way of setting this will be directly via UI.
I've created a new feature request for this which you can see at https://jira.atlassian.com/browse/FE-5718 - please feel free to add any comments to it. Also consider voting for it and adding yourself as a watcher to track its progress directly. You may refer to Atlassian's Policy about the implementation of new features.
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