Redmine

I was using the python-redmine package for creating versions ("new sprints") programatically.
To my surprise the API only supports the "due_date" but not the "start_date" which is computed from the issues.
Is there a way to force the API to accept the "start_date"?

I was looking at this code:

https://github.com/redmine/redmine/blob/master/app/models/version.rb#L71

def start_date
@start_date ||= fixed_issues.minimum('start_date')
end