https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Field%21Plugin%21Field%21FieldFormatter%21BooleanFormatter.php/10
BooleanFormatter.php | Drupal API
phpdrupalapi
https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Field%21Plugin%21Field%21FieldFormatter%21BooleanFormatter.php/class/BooleanFormatter/11.x
class BooleanFormatter | Drupal API
classdrupalapi
https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Field%21Plugin%21Field%21FieldFormatter%21BooleanFormatter.php/class/BooleanFormatter/9
class BooleanFormatter | Drupal API
classdrupalapi