code: public static function setMappings(
          array $messages,
          /*# bool */ $manual = true
      ) {
          $class = get_called_class();
  
          if ($manual) {
              // set default
              static::$messages = $messages;
  
              // status changed
              self::setStatus();
          } else {
              // set cache
              self::$mappings[$class] = array_replace(
                  $class::getMappings(),
                  $messages
              );
          }
      }
docs: Reset current message class' code to message mappings cache
  
  ```php
  MyMessage::setMappings([
  MyMessage::MSG_HELLO => 'Hello %s'
  ]);
  ```
  
  @param  array $messages messages mapping array
  @param  bool $manual manually, not auto load from $loader
  @access public
  @api