code: public static Context current() {
      Context current = storage().current();
      if (current == null) {
        return ROOT;
      }
      return current;
    }
docs: Return the context associated with the current scope, will never return {@code null}.
  
  <p>Will never return {@link CancellableContext} even if one is attached, instead a
  {@link Context} is returned with the same properties and lifetime. This is to avoid
  code stealing the ability to cancel arbitrarily.