title: keySet field in HashMap is null
body: <p>I am trying to loop over a <code>HashMap</code> with the <code>keySet()</code> method as below:</p>
  
  <pre><code>for (String key : bundle.keySet()) {
      String value = bundle.get(key);
      ...
  }
  </code></pre>
  
  <p>I use a lot of for-each loops on HashMaps in other parts of my code, but this one as a weird behavior: its size is 7 (what's normal) but <code>keySet</code>, <code>entrySet</code> and <code>values</code> are <code>null</code> (according to the Eclipse debugger)!</p>
  
  <p>The "bundle" variable is instantiated and populated as follows (nothing original...):</p>
  
  <pre><code>Map &lt;String, String&gt; privVar;
  Constructor(){
      privVar = new HashMap&lt;String, String&gt;();
  }
  public void add(String key, String value) {
      this.privVar.put(key, value);
  }
  </code></pre>