title: Filter null values after map in Java 8
body: <p>I'm new in using <code>map</code> and <code>filters</code> in Java 8. I'm currently using <code>Spark ML</code> library for some ML algorithms. 
  I have the following code:</p>
  
  <pre><code>// return a list of `Points`.
  List&lt;Points&gt; points = getPoints();
  List&lt;LabeledPoint&gt; labeledPoints = points.stream()
                                          .map(point -&gt; getLabeledPoint(point))
                                          .collect(Collectors.toList());
  </code></pre>
  
  <p>The function <code>getLabeledPoint(Point point)</code> returns a new <code>LabeledPoint</code> if the data is correct or null otherwise. How can I filter (remove) the <code>null</code> <code>LabeledPoint</code> objects after <code>map</code>?</p>