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Two suggestions to improve caching:

1. In case an entity exists you have to return a neutral access result with the correct cache data.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addCacheTags(['my_entity_list']);
  }

postDelete() and postSave() are no longer necessary.

Two suggestions to improve caching:

1. Even if you don't want to make a decision to allow or deny access you can return a neutral result to add cache metadata.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addCacheTags(['my_entity_list']);
  }

postDelete() and postSave() are no longer necessary.

Two suggestions to improve caching:

1. In case an entity exists you have to return a neutral access result with the correct cache data.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addcachetags(['my_entity_list']);
  }

postDelete() and postSave() is no longer necessary.

Two suggestions to improve caching:

1. In case an entity exists you have to return a neutral access result with the correct cache data.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addCacheTags(['my_entity_list']);
  }

postDelete() and postSave() are no longer necessary.

Two suggestions to improve caching:

1. In case an entity exists you have to return a neutral access result with the correct cache data.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addcachetags(['my_entity_list');
  }

postDelete() and postSave() is no longer necessary.

Two suggestions to improve caching:

1. In case an entity exists you have to return a neutral access result with the correct cache data.

2. The custom cache tag can be replaced by the list tag ENTITY_TYPE_list, which is invalidated automatically when entities are added or deleted.

The resulting code:

  public function access(AccountInterface $account) {
    if ($entity_does_not_exist) {
      return AccessResult::forbidden()->addCacheTags(['my_entity_list']);
    }
    return AccessResult::neutral()->addcachetags(['my_entity_list']);
  }

postDelete() and postSave() is no longer necessary.