example_module.libraries.yml in Drupal 9

core/tests/Drupal/Tests/Core/Asset/library_test_files/example_module.libraries.yml

File

core/tests/Drupal/Tests/Core/Asset/library_test_files/example_module.libraries.yml

example:
  version: VERSION
  css:
    theme:
      css/example.css: {}
      css/example2.css: {}