Using Generic List in WCF

Scenario:
I wanted to store few documentIDs in my DataMember. I thought of using Generic List, so far so good but when adding the service reference from my client application, I noticed that Generic List got converted to string[] and while compiling I got the following error

Cannot implicitly convert type 'string[]' to System.Collections.Generic.List'

Workaround:
The representation of a List is equivalent to the representation of a ArrayList. So it will just work if you use the Arraylist at the client side

Solution:
Right click the Service reference > Configure Service Reference > Select 'System.Collection.Generic.List' from Collection type drop down menu.

But i wanted to still use Generic List, so this is how i did it.
Here's the code.

IService1.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

using System.Collections;

namespace TestWCF
{
  [ServiceContract]
  public interface IService1
  {
      [OperationContract]
      CompositeType GetDataUsingDataContract(CompositeType composite);
 }

 [DataContract]
  public class CompositeType
  {
      private List<string> lists;
      [DataMember]
      public List<string> Lists
      {
          get { return lists; }
          set { lists = value; }
      }
  }
}

Service1.cs:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace TestWCF
{
  public class Service1 : IService1
  {
      public CompositeType GetDataUsingDataContract(CompositeType composite)
      {
        composite.Lists = new List<string>();
        composite.Lists.Add("D");

          return composite;
      }
  }
}

Code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TestWCFClient
{
  public partial class Form1 : Form
  {
      public Form1()
      {
          InitializeComponent();
      }

      private void Form1_Load(object sender, EventArgs e)
      {
          ServiceReference1.CompositeType composite = new ServiceReference1.CompositeType() ;
          ServiceReference1.CompositeType composite2 = new ServiceReference1.CompositeType() ;

          ServiceReference1.Service1Client sc = new ServiceReference1.Service1Client();
          composite2 = sc.GetDataUsingDataContract(composite);
          MessageBox.Show(composite2.Lists.Count.ToString());
      }
  }
}