The structure, element and attribute names of the required XML document
are hard-coded in this class. (Of course a transform could be run if necessary
to produce this format). "beans" doesn't need to be the root element of the XML
document: This class will parse all bean definition elements in the XML file.
This class registers each bean definition with the DefaultListableBeanFactory
superclass, and relies on the latter's implementation of the BeanFactory interface.
It supports singletons, prototypes, and references to either of these kinds of bean.
See "spring-beans_2_0.dtd" for details on options and configuration style.
For advanced needs, consider using a DefaultListableBeanFactory with
an XmlBeanDefinitionReader. The latter allows for reading from multiple XML
resources and is highly configurable in its actual XML parsing behavior.