Drupal Commerce Custom Line Item Types without a Product Reference Field Let me start by saying I am aware of this module: https://www.drupal.org/project/commerce_custom_product

This module works great for custom line item types that need to reference a product, however (correct me if I am wrong) this module can't be used to create custom line item types that do NOT reference a product.

I need a custom line item type, that doesn't reference a product. Which lead to the discovery of this:

http://cgit.drupalcode.org/commerce_examples/tree/line_item_example/line_item_example.module

Utilizing hook_commerce_line_item_type_info() I am able to successfully create a custom line item type, and have it automatically come with the Unit and Total price fields automatically.

All is well so far...

Now if I use the Drupal UI to add a custom field (e.g. an entity reference field, not a product reference field) to this custom line item type, I am able to do this without issue. I can add as many fields as I want.

Now for the problem...

However, when I use the admin order form and try to manually add this custom line item type to an order, the custom field(s) don't show up in the form.

I see from the documentation that I could implement the configuration, add_form and add_form_submit callbacks. But I figured any fields added through the UI would automatically show up on the form(s).

What is going on here? Must I implement the form code-side for all fields on the custom entity type?
A line item must have a product associated with it. Rules, Commerce Cart, and Commerce Shipping all depend on having the commerce_product field on a line item object.