How to properly attach a library to CheckoutPaneForm I'm attempting to attach a library to a CommerceCheckoutPane plugin.  I first started with using $pane_form['#attached']['library'][] = 'commerce_paypal/express-checkout';.  There were some errors in my commerce_paypal.libraries.yml file but once those were resolved the libaries still don't appear to be loaded.

Right now, my setup looks like:

commerce_paypal.libraries.yml:

paypal.checkout:
  remote: https://www.paypalobjects.com/api/checkout.js
  license:
    name: MIT
    gpl-compatible: true
  js:
    https://www.paypalobjects.com/api/checkout.js
express-checkout:
  js:
    js/paypal_ec.js
  dependencies:
    - commerce_paypal/paypal.checkout


Drupal\commerce_paypal\Plugin\Commerce\CheckoutPane\ExpressCheckout:

public function buildPaneForm(array $pane_form, FormStateInterface $form_state, array &amp;$complete_form) {
  $pane_form['#theme'] = 'commerce_paypal_express_checkout';

  return $pane_form;
}


commerce-paypal-express-checkout.html.twig

{{ attach_library('commerce_paypal/express-checkout') }}

asdfas


js/paypal_ec.js:

console.log('here');


When I place the pane form I see asdfas but the JS is not added.  I've checked the source, no sign of paypal_ec.js.
As usual, I was messing something up.  JS libraries need : {}.  Updating commerce_paypal.libraries.yml to this solves it:

paypal.checkout:
  remote: https://www.paypalobjects.com/api/checkout.js
  license:
    name: MIT
    gpl-compatible: true
  js:
    https://www.paypalobjects.com/api/checkout.js: {}
express-checkout:
  js:
    js/paypal_ec.js: {}
  dependencies:
    - commerce_paypal/paypal.checkout