Javadoc
This method returns a namespace context object that contains
information identical to that returned by
javax.xml.stream.XMLStreamReader#getNamespaceContext(),
but one that is
not transient. That is, one that will remain valid and unchanged
after its creation. This allows the namespace context to be used
independent of its source documents life cycle. One possible use
case is to use this namespace context for 'initializing' writers
(especially ones that use repairing mode) with optimal/preferred name
space bindings.