Drupal/legacy table to Symfony Doctrine entity

.env.local

DATABASE_URL=mysql://db:db@localhost/db?sslmode=disable&charset=utf8mb4&serverVersion=5.7
DATABASE_DRUPAL_URL=mysql://db:db@localhost/legacy?sslmode=disable&charset=utf8mb4&serverVersion=5.7

doctrine.yaml

# config/packages/doctrine.yaml
doctrine:
    dbal:
        default_connection: default
        connections:
            default:
                url: '%env(resolve:DATABASE_URL)%'
            drupal:
                url: '%env(resolve:DATABASE_DRUPAL_URL)%'
                schema_filter: /^(table_name)$/

    orm:
        auto_generate_proxy_classes: true
        default_entity_manager: default
        entity_managers:
            default:
                auto_mapping: true
                naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
                connection: default
                mappings:
                    App:
                        is_bundle: false
                        type: annotation
                        dir: '%kernel.project_dir%/src/Entity'
                        prefix: 'App\Entity'
                        alias: App
            drupal:
                connection: drupal
                mappings:
                    App:
                        is_bundle: false
                        type: annotation
                        dir: '%kernel.project_dir%/src/Entity/Drupal'
                        prefix: 'App\Entity\Drupal'
                        alias: App

Create folder "src/Entity/Drupal".
Run php bin/console doctrine:mapping:import "App\\Entity\\Drupal" annotation --em=drupal --path=src/Entity/Drupal --force