title: How to merge multiple maps into one in Spring
body: <p>I have several maps defined in my context file.  Is there a way to combine those maps into one map that contains all of their entries, without writing Java code (and without using nested maps)?  I'm looking for the equivalent of Map m = new HashMap(); m.putAll(carMap); m.putAll(bikeMap); 
  Seems like there should be a way to do this in Spring context file, but the Spring 3.0 reference doc section on util:map doesn't cover this use case.</p>
  
  <pre><code>&lt;!-- I want to create a map with id "vehicles" that contains all entries of the other maps --&gt;
  
  &lt;util:map id="cars"&gt;
      &lt;entry key="groceryGetter" value-ref="impreza"/&gt;
  &lt;/util:map&gt;
  
  &lt;util:map id="bicycles"&gt;
      &lt;entry key="commuterBike" value-ref="schwinn"/&gt;
  &lt;/util:map&gt;
  </code></pre>