OR-Tools employee scheduling: maximising consecutive shifts

Question

I've been studying the OR-Tools Employee Scheduling example and would like to change it so that the model would allow employees to be assigned to multiple shifts per day and at the same time give preference to solutions where an employee is assigned consecutive shifts within the span of a given day. Allowing multiple shifts seems straightforward, but how can I define an objective function that would prefer consecutive shifts? I don't want consecutiveness to be a hard constraint for the solution.