Do not allow empty string for media descriptor. For the sake of clearness NULL should be used for a missing value. This avoids extra checks e.g. for generating LAF exports. The CHECK constraints in the database could be more elaborate.

<?xml version="1.0"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://jboss.org/schema/cdi/beans_1_0.xsd"/>