/**
  * @inheritdoc
  */
 public function init()
 {
     foreach (['username', 'apiKey', 'containerName', 'region'] as $attribute) {
         if ($this->{$attribute} === null) {
             throw new InvalidConfigException(strtr('"{class}::{attribute}" cannot be empty.', ['{class}' => static::className(), '{attribute}' => '$' . $attribute]));
         }
     }
     parent::init();
 }
 /**
  * @inheritdoc
  */
 public function init()
 {
     foreach (['key', 'secret', 'bucket'] as $attribute) {
         if ($this->{$attribute} === null) {
             throw new InvalidConfigException(strtr('"{class}::{attribute}" cannot be empty.', ['{class}' => static::className(), '{attribute}' => '$' . $attribute]));
         }
     }
     parent::init();
 }