Add #stream to sets: - #1088

A simple non-splittable implementation is OK for the sets are not
currently sized.

Overview

See: https://jira.bf.local/browse/ECR-XYZ

Definition of Done

• There are no TODOs left in the code
• Change is covered by automated tests
• The coding guidelines are followed
• Public API has Javadoc
• Method preconditions are checked and documented in the Javadoc of the method
• Changelog is updated if needed (in case of notable or breaking changes)
• The continuous integration build passes