title: .keys() method not working on JSONObject eclipse
body: <p>i am trying to use the .keys() method to get the name of JSON Object's 
  the code im using is;</p>
  
  <pre><code>Iterator&lt;String&gt; keys = JSONObject.keys();
  </code></pre>
  
  <p>.keys() is underelined as red on eclipse, i dont know why, can any one help, thanks! - </p>
  
  <p><a href="https://i.stack.imgur.com/qmyaa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qmyaa.png" alt="enter image description here"></a></p>
  
  <p>I have JSON simple as an external library and have imported it, not sure what else to do</p>
  
  <p>EDIT:</p>
  
  <p>Here is more code; </p>
  
  <pre><code>    JSONParser parser = new JSONParser();
              FileReader testfile = new FileReader("test2.txt");
              Object obj = parser.parse(testfile); 
              JSONObject jsonObject = (JSONObject) obj;
              JSONObject name = (JSONObject) jsonObject.get("txt");
              String time = (String) name.get("name");
              JSONObject example2 = (JSONObject) jsonObject.get("birth");
              System.out.println(example2);
  
  
  
          Iterator keys = example2 .keys(); &lt;-- where the red line shows up
  </code></pre>
  
  <p>Second edit:
  here are my imports.</p>
  
  <pre><code> import java.io.FileReader;
      import java.io.IOException;
      import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.nio.file.StandardCopyOption;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.Set;
  import org.json.simple.JSONObject;
  import org.json.simple.parser.JSONParser;
       import org.json.simple.parser.ParseException;
  </code></pre>