title: Is there an aggregateBy method in the stream Java 8 api?
body: <p>Run across this very interesting but one year old <a href="http://youtu.be/X2MtmIa7YSs?t=35m39s" rel="nofollow noreferrer">presentation</a> by Brian Goetz - in the slide linked he presents an <code>aggregateBy()</code> method supposedly in the Stream API, which is supposed to aggregate the elements of a list (?) to a map (given a default initial value and a method manipulating the value (for duplicate keys also) - see next slide in the presentation).</p>
  
  <p>Apparently there is no such method in the <a href="http://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html" rel="nofollow noreferrer">Stream API</a>. Is there another method that does something analogous in Java 8 ?</p>