title: Implement search with multiple maps
body: <p>I have this multimap with Guava which I would like to implement with multiple maps in order to make key-value search:</p>
  
  <pre><code>String key = "first-key";
          Multimap&lt;String, String&gt; map = ArrayListMultimap.create();
  
          map.put(key, "firstValue");
          map.put(key, "secondValue");
          map.put(key, "thurdValue");
  
          map.putAll("sec-key", Sets.newHashSet("am", "are", "is"));
  
          for (String name : map.keySet()) {  
             System.out.println("key: " + name); 
          }
  </code></pre>
  
  <p>I tried this:</p>
  
  <pre><code>Map&lt;String, String&gt; map1 = new HashMap&lt;String,String&gt;();
          Map&lt;String, Map&lt;String, String&gt;&gt; map2 = new HashMap&lt;String, Map&lt;String, String&gt;&gt;();
          Map&lt;String, Map&lt;String, Map&lt;String, String&gt;&gt;&gt; map3 = new HashMap&lt;String, Map&lt;String, Map&lt;String, String&gt;&gt;&gt;();
  
          map3.put("AF", Map.of("Afghanistan", Map.of("AFG", "004")));
  </code></pre>
  
  <p>How for example I can search for key <code>Afghanistan</code> and get value <code>AFG</code>?</p>
  
  <p>Is there some better way to implement this?</p>