Goal / high level use-case
I would like to know that a connection is guaranteed in an itinerary, and to have an exception for tight connection times for guaranteed connection.

Describe the solution you'd like
In the journey planner input, I would like to have a flag to disable the transferSlack for guaranteed connections.

In the itinerary output, I would like to have a flag which indicates that it is a guaranteed connection from the previous transit leg.

Describe alternatives you've considered
N/A

Additional context
N/A