title: google dataflow: the type Sum.SumIntegerFn is not visible
body: <p>In my Eclipse, I've got flagged with error " The type Sum.SumIntegerFn is not visible.</p>
  
  <pre><code>import org.apache.beam.sdk.transforms.Sum;
  ....
  something = createAggregator("something", new Sum.SumIntegerFn());
  </code></pre>