Which spring property to control concurrent transactions?

I have a Spring application. The application allows user to create a Project related information to the DB and also allows the user to edit those projects.

How can I introduce the following:

9 PM - User 1 starts to edit the project P1. 9:10 PM - User 2 begins to edit the same project P1. 9:15 PM - User 1 saves his work in the DB. 9:16 PM - User 2 tries to save his work. He won't be allowed to save as the record has changed (9:15 PM) since he started to edit the record (9:10 PM).