[kaba0]

You are talking about JPA entities, javabeans are nothing more than objects managed by an application server (or nowadays without them as well with spring boot), whose instances can be queried and loaded dynamically. It is basically a huge map of strings to java objects, and objects range from database connections (which were then configured outside of the program, making configuration decoupled, e.g. at deployment one could even change connection pooling, database vendor, etc) to remote objects on another computer to ldap to.. well, anything.