Select and expand the newly-created Localizations item.
For each locale your application supports,
add a new item and select the locale you wish to add
from the pop-up menu in the Value field.
This list should be consistent with the languages listed
in the supportedLocales parameter.

Once all supported locales have been added, save the file.

Advanced topics for further customization

This section covers additional ways to customize a
localized Flutter application.

Advanced locale definition

Some languages with multiple variants require more than just a
language code to properly differentiate.

For example, fully differentiating all variants of
Chinese requires specifying the language code, script code,
and country code. This is due to the existence
of simplified and traditional script, as well as regional
differences in the way characters are written within the same script type.

In order to fully express every variant of Chinese for the
country codes CN, TW, and HK, the list of supported
locales should include: