Issue #2335879 by alexpott, dixon_, Wim Leers, chx, mauzeh, ygerasimov, jeqq: Change SqlContentEntityStorageSchema::requiresEntityDataMigration() to ask the old storage handler if it has data rather than assuming yes unless NULL storage

Issue #2296115 by jhodgdon, hussainweb: Fixed Several entity loadRevision() methods do not obey the interface contract.

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().