Server validation for unique fields

[HegelPro]

Environment
Restapi version: 7.2.2

1. Create Entity with an Unique Field
   

2. If Entity with the unique field already exist
   
   

3. Try to add new Entity with existing unique
   
   

Need meta information about type error(e.g. UniqueValueError) and in which fields happened error. This will help to handle the error.