title: Java 8 Stream List into map with identical values
body: <p>I'm in a bizarre situation. Is there anyway to stream a List to a map with identical values?</p>
  
  <p>i.e.</p>
  
  <p>let <code>a</code> be of type <code>Map&lt; Integer, List&lt; String &gt; &gt;</code></p>
  
  <p>let's say <code>b</code> is just a list of integers that correspond to the keys of <code>a</code>.</p>
  
  <pre><code>b.stream().map(x -&gt;
      a.get(x).stream()
          .collect(
              Collectors.toMap(i -&gt; i, x);
          )
  );
  </code></pre>
  
  <p>I want a map where all the values are an <code>x</code> and all the keys are from the values in <code>b</code>.</p>
  
  <p>The above function is supposed to return a <code>Stream&lt; List&lt; Map&lt; String, Int &gt; &gt; &gt;</code> (obviously it doesn't work)</p>