Cache using Symfony's Cache logic as it is already available.

It's "its", not "it's". And I think, without noticing, you raise another good question here. According to the Drupal coding standards acronyms should also be camelcase, which would make this the DicBuilder class. But I will open a separate issue for this since this also has impact on the DIC class itself... Meanwhile you can use the DICBuilder classname in this comment.