Inclusion of unused namespace declarations in marshalled XML

Question

Hello.
I have noticed that by default any XML marshaled from an object contains namespace declarations related to every package specified when instantiating the JAXBContext even though they are not used in the instance being marshalled.
Is there any way to avoid this during the marshalling as opposed to via some sort of post processing (e.g. XSLT transform).
Example source below:
package test;
import javax.xml.bind.*;
import java.io.*;
import test.sample1.*;
import test.sample2.*;
public class Converter {
     public static void main(String[] args) {
          try {
               String sample1 = "<Message1 xmlns=\"http://www.example.org/sample1\">" +
                                         "<tns:Field xmlns:tns=\"http://www.someother.org\">value</tns:Field>" +
                                    "</Message1>";
               String sample2 = "<Message2 xmlns=\"http://www.example.org/sample2\">" +
                                        "<Field1>value1</Field1>" +
                                        "<Field2>value2</Field2>" +
                                    "</Message2>";
               JAXBContext ctx = JAXBContext.newInstance("test.sample1:test.sample2");
               Unmarshaller um = ctx.createUnmarshaller();
               Marshaller m = ctx.createMarshaller();
               StringWriter sw1 = new StringWriter();                
               Message1 msg = (Message1)um.unmarshal(new StringReader(sample1));
               m.marshal(msg, sw1);               
               System.out.println("Marshalled sample1: \n"+sw1.toString());
               StringWriter sw2 = new StringWriter();                
               Message2 msg2 = (Message2)um.unmarshal(new StringReader(sample2));
               m.marshal(msg2, sw2);               
               System.out.println("Marshalled sample2: \n"+sw2.toString());
          } catch (JAXBException e) {
               e.printStackTrace();
}Produces output:-
Marshalled sample1:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Message1 xmlns:ns2="http://www.example.org/sample2" xmlns="http://www.example.org/sample1"><tns:Field xmlns:tns="http://www.someother.org">value</tns:Field></Message1>
Marshalled sample2:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><ns2:Message2 xmlns:ns2="http://www.example.org/sample2" xmlns="http://www.example.org/sample1"><ns2:Field1>value1</ns2:Field1><ns2:Field2>value2</ns2:Field2></ns2:Message2>

Answer 1

Thanks for the quick response. I really appreciate it.
Yes, as you say, there is no real problem as such but part of my app lets the user see the RAW message XMLs and this could confuse them and would be tidier to remove but I can also see why it is easier from the Marshaller perspective not to have to back track to remove unused declarations.
Also, I'm a little concerned about the increased size of the XML produced. One of my webservices does handle quite a few different types and our Oracle namespace URLs are all pretty long!
Like I say, I can see a way to get rid of them after the fact but wondered if there was a more elegant/performant way.