title: Java convert {String,String}[] to Map<String,String[]>
body: <p>Given the class:</p>
  
  <pre><code> public class CategoryValuePair
   {
        String category;
        String value;
   }
  </code></pre>
  
  <p>And a method:</p>
  
  <pre><code>public Map&lt;String,List&lt;String&gt;&gt; convert(CategoryValuePair[] values);
  </code></pre>
  
  <p>Given that in <code>values</code> we can receive many entries with the same category, I want to convert these into a <code>Map</code> grouped on category.</p>
  
  <p>Is there a quick / efficient way to perform this conversion?</p>