https://api.drupal.org/api/drupal/core%21modules%21migrate%21src%21Plugin%21migrate%21destination%21EntityContentBase.php/property/EntityContentBase%3A%3AentityFieldManager/8.9.x
EntityContentBase::$entityFieldManager | Drupal API
drupalapi
https://api.drupal.org/api/drupal/core%21modules%21migrate%21src%21Plugin%21migrate%21destination%21EntityContentBase.php/8.9.x
EntityContentBase.php | Drupal API
phpdrupalapi