Erro usando action

package br.com.cfr.action;

import java.util.List;

import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Result;

import br.com.cfr.jdbc.dao.TarefaDAO;
import br.com.cfr.jdbc.modelo.Tarefa;


public class ListaTarefasAction {
	
	private List<Tarefa> tarefas;
	
	
	@Action(value="lista", results= {
	@Result(name="ok", location="lista-tarefas.jsp")
	})
	public String execute() throws ClassNotFoundException {
	tarefas = new TarefaDAO().lista();
	return "ok";
	}
	public List<Tarefa> getTarefas() {
	return tarefas;
	}
	
}

package br.com.cfr.jdbc.dao;

  
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.Date;

import br.com.cfr.jdbc.ConnectionFactory;
import br.com.cfr.jdbc.modelo.Tarefa;
 
public class TarefaDAO { 
     
    Connection connection; 
     
    public TarefaDAO() throws ClassNotFoundException{ 
        this.connection = new ConnectionFactory().getConnection(); 
    } 
     
    public void adiciona (Tarefa tarefa){ 
         
        String sql = "insert into tab_tar (descricao , finalizado) value(?,?)"; 
         
        try { 
            PreparedStatement stmt = connection.prepareStatement(sql); 
            stmt.setString(1, tarefa.getDescricao()); 
            stmt.setString(2, tarefa.getFinalizado());
            
             
            stmt.execute(); 
            stmt.close();                
        } catch (SQLException e){ 
            throw new RuntimeException (e); 
        } 
         
         
         
    }
 
     
 
      public List<Tarefa> lista() {
            try {
                  List<Tarefa> tarefas  = new ArrayList<Tarefa>();
                  PreparedStatement stmt = this.connection.prepareStatement("select * from tab_tar");
                  ResultSet rs = stmt.executeQuery();
                 
                  while (rs.next()){
                       
                        Tarefa tarefa = new Tarefa();
                        tarefa.setId(rs.getLong("id"));
                        tarefa.setDescricao(rs.getString("descricao"));
                        tarefa.setFinalizado(rs.getString("finalizado"));
                        
                        Calendar data = Calendar.getInstance();
        				data.setTime(rs.getDate("dataFinalizacao"));
        				tarefa.setDataFinalizacao(data);
                       
                        tarefas.add(tarefa);
                  }
                  rs.close();
                  stmt.close();
                  return tarefas;  
                 
            } catch (SQLException e) {
            	
            	throw new RuntimeException(e);
            }    
      }
 
      public void remove(Tarefa tarefa) {
           
            try {
                  PreparedStatement stmt = connection.prepareStatement("delete from tab_tar where id=?");
                  stmt.setLong(1, tarefa.getId());
                  stmt.execute();
                  stmt.close();
            } catch (SQLException e) {
                  throw new RuntimeException(e);
            }
    }
           
      }