Custom Validation code walkthrough

Billing System using Spring Boot. Custom validation. Code walkthrough

Why I have chosen custom validation for registration flow rather than Spring Boot validation.

The reason is, I have to use the Following three DTO classes for creating for new Employee, Customer, and Vendor Object. These DTO act as the request Body
EmployeeDTO,
VendorDTO,
CustomerDTO,
For further reading, please read this story from this blog. Custom Validation