Model
Container
Magento\Usps\Model\Source\Container
What it does
This class provides a source model for USPS shipping container types in Magento 2's admin configuration.
Developers use this to populate dropdown options for selecting USPS package containers (like flat rate boxes, envelopes, etc.) in the shipping settings.
It extends the Generic source class and identifies itself with the 'container' code to retrieve USPS-specific container options.