How to implement batch fetching with Fluent NHibernate when working with Oracle?

To give you the answer how to use batching with fluent:

1) on the colleciton

HasMany<MyEntity>(x => x.Entities)
  .BatchSize(100);

2) on a class level

public MyEntityMap()
{
    Id(x => x....
    ...
    BatchSize(100);

This corresponds with the 19.1.5. Using batch fetching