Yo uso JAXB para crear carpetas y archivos de jerarquía

Mi modelo:

@XmlRootElement
public class Root {

    @XmlAttribute
    private String path;

    @XmlElement(name = "dir")
    private ArrayList<Dir> rootContentDirs = null;

    @XmlElement(name = "file")
    private ArrayList<FileObj> rootContentFiles = null;


    public void setRootContentDirs(ArrayList<Dir> rootContentDirs) {
        this.rootContentDirs = rootContentDirs;
    }

    public void setRootContentFiles(ArrayList<FileObj> rootContentFiles) {
        this.rootContentFiles = rootContentFiles;
    }

    public void setPath(String path) {
        this.path = path;
    }
 }

public class Dir {

    @XmlAttribute
    private String name;

    @XmlElement(name = "dir")
    private ArrayList dirs = null;

    @XmlElement(name = "file")
    private ArrayList files = null;

    public void setName(String name) {
        this.name = name;
    }

    public void setDirs(ArrayList dirs) {
        this.dirs = dirs;
    }

    public void setFiles(ArrayList files) {
        this.files = files;
    }
 }

public class FileObj{

   @XmlAttribute
   private String name;
   @XmlAttribute
   private long size;
   @XmlAttribute
   private String type;


   public void setName(String name) {
       this.name = name;
   }

   public void setSize(long size) {
       this.size = size;
   }

   public void setType(String type) {
       this.type = type;
   }
}

Quiero hacer un árbol de directorios y archivos:

public class XmlByJaxb extends Generator {

private static final String JAXB_XML = "./jaxb.xml";
private static Root root = null;

@Override
public void output() throws IOException {
    JAXBContext context = null;
    Marshaller m = null;
    try {
        context = JAXBContext.newInstance(Root.class, Dir.class, FileObj.class);
        m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        m.marshal(root, new File(JAXB_XML));
    } catch (JAXBException e) {

    }
}

@Override
public void run() {
    ArrayList<FileObj> rootFiles = addFiles(dir);
    ArrayList<Dir> rootDirs = make(dir);

    root = new Root();
    root.setPath(dir.getPath());
    root.setRootContentFiles(rootFiles);
    root.setRootContentDirs(rootDirs);
/.../
}

Pero tengo un extraño "xsi: type" y "xmlns: xsi" en el xml generado:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root path="/home/phlamey/IdeaProjects/FileUtillite">
<dir name="src">
    <dir xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="dir" name="test">
        <dir xsi:type="dir" name="java">
            /.../ 

Entonces, mi pregunta: ¿qué significa esto y cómo se elimina esto?