https://medium.com/@joshirohit100/cache-context-drupal-8-part-2-10088f67012e
https://medium.com/@joshirohit100/cache-context-drupal-8-part-1-55303ec665ce
主要是通过类名和service名字来植入。
https://medium.com/@joshirohit100/cache-context-drupal-8-a-buggy-code-story-f5809596a9ff
