test written, but the validation expression is not yet correct

src/Bundle/ChillPersonBundle/Entity/AccompanyingPeriod.php

@@ -50,7 +50,7 @@ use UnexpectedValueException;
  * })
  * @Assert\GroupSequenceProvider
  * @Assert\Expression(
- *     "this.isConfidential and this.getUser === NULL",
+ *     "this.isConfidential && this.getUser && this.getStep === 'CONFIRMED'",
  *     message="If the accompanying course is confirmed and confidential, a referrer must remain assigned."
  * )
  */