JAXB - How to add xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance

Question

I am using JAXB to create XML file from a result set.

I have created java/ /class files using the xsd with the help of xjc utiliy. Now I am trying to create the xml file using the Marshaller. In the XML file I do not see the xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" attribute with the root tag.

public class JAXBConstructor
 {  
  public void generateXMLDocument(File xmlDocument){
   try 
      {
         JAXBContext  jaxbContext = JAXBContext.newInstance("com");                 
         Marshaller marshaller = jaxbContext.createMarshaller();    
         marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true); 
         marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); 
         com.ObjectFactory factory = new com.ObjectFactory();
         USERTASKSImpl  userTasks =(USERTASKSImpl)(factory.createUSERTASKS());         
         USERTASKTypeImpl userTaskType = (USERTASKTypeImpl)(factory.createUSERTASKSTypeUSERTASKType());         
         userTaskType.setName("zmannan");
         userTaskType.setCode("G5023920");
         java.util.List userTaskList=userTasks.getUSERTASK();         
         userTaskList.add(userTaskType);         
         marshaller.marshal(userTasks, new FileOutputStream("User_Task.xml"));
}

Output of the code : This does not contain the XMLSchema value -

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<USER_TASKS xmlns="http://schemas.jpmchase.net/Recertification"&gt;
    <USER_TASK>
        <Code>G5023920</Code>
        <Name>zmannan</Name>
    </USER_TASK>
</USER_TASKS>

Please help how can I add the schema-instance value in the root tag.