What are POJOs and what?s their significance?
In POJO (Plain Old Java Object) class object there are three types of states i.e. Transient state, Persistent state and Detached state. In PoJo is a programming model that adopt some simple rules to create a classes that applies the entities of the business problem. The Pojo Class is Implement a default (no-argument) constructor, Give(optional) an identifier property, prefer(optional) a non-final classes etc.
For clear concepts about Pojo of hibernate visit below link: