BlockedIp::import violates MigrateDestinationInterface::import

Problem/Motivation

\Drupal\ban\Plugin\migrate\destination\BlockedIp migrate destination plugin's import method violates \Drupal\migrate\Plugin\MigrateDestinationInterface::import, because it doesn't return anything (so its return value is NULL. This triggers a migration message in MigrateExecutable.

Steps to reproduce

Execute d7_blocked_ips migration and then check the migration messages.

Proposed resolution

Since the IPs are unique, and since the destination plugin already declares that it identifies the migrated rows with the blocked IP address, add a return statement:
return ['ip' => $row->getDestinationProperty('ip')];

Remaining tasks

Patch + test.

User interface changes

Nothing.

API changes

Nothing.

Data model changes

Nothing.

Release notes snippet

Not needed.