If you are using hibernate  3 annotations in your project you don't need any extra plugin  just use the EJB3 features witch are available in most of IDEs like Intellij Idea, Netbeans, JDeveloper, ...

For example in the Intellij idea  you just need to create your hibernate mapping class with the "Generate Persistence Mapping" feature in the Idea and it will generate all the accessors and annotations for you depending on the defined datasource and database table.
But if you are not using hibernate annotations in your project, you can use other plugins like "Hibernate Tools for eclipse".