Issue #3296987 by Yujiman85, lucassc, gquisini, diegors, joachim, cilefen: CacheableDependencyInterface::getCacheMaxAge does not document \Drupal\Core\Cache\Cache::PERMANENT

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2483781 by borisson_, rbayliss, cilefen, mitalimehta, joshi.rohit100: Move cache contexts classes from \Drupal\Core\Cache to \Drupal\Core\Cache\Context

Issue #2468151 by lhangea, rpayanm, Palashvijay4O: Rename the CacheContexts service to CacheContextsManager

Issue #2444231 by Wim Leers, nlisgo: Fix CacheableInterface so it makes sense (was: "Make Config objects & Entities implement CacheableInterface + add BubbleableMetadata::createFromCacheableObject()")

Issue #2329101 by Wim Leers: CacheableInterface only has a getCacheKeys() method, no getCacheContexts(), leads to awkward implementations

Issue #2167039 by likin, dawehner, Wim Leers, tstoeckler, vijaycs85: Regression: page cache tags broken, also: some routes incorrectly use _controller -> No page object in template variables -> Fatal in seven_preprocess_page().