XMLDescriptor descriptor = new XMLDescriptor();
descriptor.setJavaClass(StoredProcedureArgument.class);
// need policy 'cause TreeBuilder cannot use default constructor
descriptor.setInstantiationPolicy(new StoredProcedureArgumentInstantiationPolicy(this,
StoredProcedureArgumentType.STORED_PROCEDURE_ARG));
descriptor.descriptorIsAggregate();
descriptor.setDefaultRootElement("argument");
descriptor.getInheritancePolicy().setClassIndicatorField(new XMLField("@xsi:type"));
descriptor.getInheritancePolicy().addClassIndicator(StoredProcedureArgument.class,
getPrimaryNamespaceXPath() + "procedure-argument");