How to access or configure the task partition calculator for the MongoDB-Spark connector?

[alexDeCastroAtGit]

I noticed that depending on the collection size the partition calculator submits a task list that is a function of the collection size.

How could I for example set a fix number of tasks? How to access the partition calculator function and customize the partition variables?

I'd like to have a smaller number or task assignments for prototyping or testing purposes.