Add field to DFP module I need to add a &lt;div&gt; wrapper with a specific ID to a DFP AD tag within the block.

The DFP Module appears to create AD tags as entities. I cannot determine where the AD tags are stored or how to create another field to the AD tag entity that I can pull out in a preprocess function to send to my template.

I am hacking the DFP module.

Does anyone have a pointer on where to start?
If you look in the source code of the module you find that tag is a configuration entity (http://cgit.drupalcode.org/dfp/tree/src/Entity/Tag.php). This type of entities are not fieldable like content entities. But you can add custom fields by altering the config form and store the added fields in your module configuration.

Here is a how-to for this:

https://www.webomelette.com/drupal-8-custom-data-configuration-entities-using-thirdpartysettingsinterface