Symfony version(s) affected: 4.1.0

Description
According to the documentation you can use {{ value }} in message option to display a string representation of the invalid entity using the __toString method of the entity class.
I have implemented the __toString method but I'm getting this kind of message "Object of class CLASS identified by "

Possible Solution
I have checked this code but I can't figure out where is the __toString method called. It can be fixed checking if the entity class is implementing __toString before adding the default message.