Setting status code when validation fails.

[chainhead]

I am working with this project where Hibernate is used for validation. I didn't enter any information on the UI and I get a valid response message as below.

{"message":"Author has been very lazy, Author cannot be blank, Title cannot be blank","success":false}

However, the HTTP status code is not consistent across three different validation mechanisms as shown below.

Option	HTTP status code
Manual validation	200
End-point validation	400
Service method validation	200

Is this valid behavior?