A request wrapper that allows modification to parameter map

CustomRequestWrapper.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class CustomRequestWrapper extends HttpServletRequestWrapper {

	private HttpServletRequest wrapped;

	private Map<String, String[]> parameterMap;

	public CustomRequestWrapper(HttpServletRequest wrapped) {
		super(wrapped);
		this.wrapped = wrapped;
	}

	public void addParameter(String name, String value) {
		if (parameterMap == null) {
			parameterMap = new HashMap<String, String[]>();
			parameterMap.putAll(wrapped.getParameterMap());
		}
		String[] values = parameterMap.get(name);
		if (values == null) {
			values = new String[0];
		}
		List<String> list = new ArrayList<String>(values.length + 1);
		list.addAll(Arrays.asList(values));
		list.add(value);
		parameterMap.put(name, list.toArray(new String[0]));
	}

	@Override
	public String getParameter(String name) {
		if (parameterMap == null) {
			return wrapped.getParameter(name);
		}

		String[] strings = parameterMap.get(name);
		if (strings != null) {
			return strings[0];
		}
		return null;
	}

	@Override
	public Map<String, String[]> getParameterMap() {
		if (parameterMap == null) {
			return wrapped.getParameterMap();
		}

		return Collections.unmodifiableMap(parameterMap);
	}

	@Override
	public Enumeration<String> getParameterNames() {
		if (parameterMap == null) {
			return wrapped.getParameterNames();
		}

		return Collections.enumeration(parameterMap.keySet());
	}

	@Override
	public String[] getParameterValues(String name) {
		if (parameterMap == null) {
			return wrapped.getParameterValues(name);
		}
		return parameterMap.get(name);
	}

}

Hola, como utilizo esta clase? How I can use this class?