Combination of XML and Reflection API

I am writing this blog because I am fond of Reflection API. The XML off course is interesting in itself.
I am working in a product based company. There are many versions of our product. And each version has lots of changes for a particular feature.
To support a feature for every version, these days I am involved in developing general tools which support all versions. I am using lot of XML to develop
such tools.
I want to share an example which uses XML and Reflection to solve many problems, especially in developing general tool and unit testing.

I have a set of methods to be executed with various parameters. Here is the operation.xml.
<root>
  <oper method="add">
    <param>10</param>
    <param>20</param>
  </oper>

  <oper method="sub">
    <param>50</param>
    <param>10</param>
  </oper>

  <oper method="getName">
    <param>Example</param>
  </oper>
</root>

My methods are defined in Operation.java

public class Operation {
  public int add(String a, String b) {
    return Integer.parseInt(a) + Integer.parseInt(b);
  }

  public int sub(String a, String b) {
    return Integer.parseInt(a) - Integer.parseInt(b);
  }

  public String getName(String name) {
    return "Hello " + name;
  }
}

Now my Main class, which will use XML, calls methods of Operation.java accordingly.

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class Main {
  public static void main(String[] args) {
    Document document = null;
    SAXReader reader = new SAXReader();
    try {
      document = reader.read("operation.xml");
    } catch (DocumentException e) {
      e.printStackTrace();
    }

    Element root = document.getRootElement();
    Iterator operIterator = root.elementIterator("oper");
    Main main = new Main();
    while(operIterator.hasNext()) {
      main.processOper(operIterator.next());
    }
  }

  private void processOper(Element oper) {
    String method = oper.attributeValue("method");
    List