ConfigurationContainer.configuration should be of type Xpp3Dom, not Object

All references to ConfigurationContainer.configuration, including the get/setConfiguration methods, treat it as a org.codehaus.plexus.util.xml.Xpp3Dom instance. Yet the signature is Object, and the Javadoc does not even mention the actual type. This is confusing and error-prone.

Suggest changing the signature throughout to Xpp3Dom. If this cannot be done for reasons of binary compatibility, I would suggest: change the signature of the field; introduce a new setConfiguration(Xpp3Dom); @Deprecate setConfiguration(Object) and make it just call setConfiguration(Xpp3Dom) after casting; and update the Javadoc of getConfiguration to specify that it will always return an Xpp3Dom instance (or maybe null). (While the JVM is happy to have two no-arg methods with the same name but different return types, javac will not allow it; possible only by postprocessing bytecode.) Could also introduce new method names, e.g. get/setConfigurationDom.

It seems that the bug may ultimately be in modello-plugin-java for handling <type>DOM</type> poorly. (JavaModelloGenerator, introduced by brett, commented on by demers.)