Grouping by collector

[OLBEA20]

AS a user of Jivago Streams I would like to be able to perform a grouping by reduction on my streams SO that I can perform more advanced functional style actions.

Example of desired behavior:

class Person: 
  age: int,
  name: string

people: List[Person] = [{age: 10, name: Toto}, {age:10, name: Bob}, {age:12, name: Julie}]

people_grouped_by_age = Stream(people).gouping_by(person.age) \Not sure if person.age could be accessed just like that

print(people_grouped_by_age)
Output: [[{age: 10, name:Toto}, {age: 10, name: Bob}], [{age:12, name:Julie}]]

Java doc: https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html