Spring: properties añadiendo valores a las del sistema

<bean id="systemPrereqs"
    class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject" value="#{@systemProperties}" />
    <property name="targetMethod" value="putAll" />
    <property name="arguments">
        <!-- The new Properties -->
        <util:properties>
            <prop key="java.security.auth.login.config">/super/secret/jaas.conf</prop>
        </util:properties>
    </property>
</bean>