The starting point
Maven-bshd5 starts from Hibernate mapping files (.hbm.xml). There are different ways to obtain them.
For example you can write manually these files :-) or automate their production.
If you are in a top-down process, from abstract UML model to concrete -Java code and database installation scripts- you can use http://xdoclet.sourceforge.net/ and its hibernate-doclet module.
Instead if you start from bottom to up, so you have the database and you need to abstract, you can use http://tools.hibernate.org Ant's task hbm2java.
How use the plugin
Note
The plugin put generated files in /target/hibernatetools/ so you need manually move them in /src/main/java.