Some configuration is shared across many projects and duplication must be avoided, e.g. for hibernate configuration this can be achieved using ArrayList for properties of type List and a custom class HibernateProperties for properties of type Properties.

    
        
            
        
        
            
        
        
            
        
    

    
        
            
                ${hibernate.dialect}
                ${hibernate.show_sql}
                ${hibernate.hbm2ddl.auto}
            
        
    

    
        
            
                net/sf/oness/party/model/party/bo/Party.hbm.xml
            
        
    

This way mappingResources can be overriden in each project for their set of classes and hibernateProperties can also be overriden to get values from JNDI as I do in the ONess project.