The base component is implicit and
    need not be defined in the pubspec.

Assets can also be included by adding
    an assets section in the deferred component configuration:
    
  deferred-components:
    - name: boxComponent
      libraries:
        - package:MyAppName/box.Dart
      assets:
        - assets/image.jpg
        - assets/picture.png
          # wildcard directory
        - assets/gallery/
    

    An asset can be included in multiple deferred components,
but installing both components results in a replicated asset.
Assets-only components can also be defined by omitting the
libraries section. These assets-only components must be
installed with the DeferredComponent utility class in
services rather than loadLibrary().
Since Dart libs are packaged together with assets,
if a Dart library is loaded with loadLibrary(),
any assets in the component are loaded as well.
However, installing by component name and the services utility
won’t load any dart libraries in the component.