title: How to remove a specific value/rows from an inner map of an outer map in Guava Multi Map
body: <p>I wanted to remove specific keys from my inner multimap <strong>"car_model_id"</strong> that has a char value <strong>'Y'</strong> contained from the <strong>DetailClass</strong>'s instance variable <strong>"flag"</strong> by querying via the outer maps key.</p>
  
  <pre><code>   // Outermap:
     Multimap&lt;Long, Multimap&lt;Integer, DetailClass&gt;&gt; car_manufacturer_id = ArrayListMultimap.create();
  
     // Innermap:
     Multimap&lt;Integer, DetailClass&gt; car_model_id = ArrayListMultimap.create();
  
     // DetailClass instance variables
     attr_key, serial, flag, state
  
     // Inserting Values to Inner Map
      car_model_id.put(1, new DetailClass(1016,'PO-90','Y',"TX"));
      car_model_id.put(1, new DetailClass(1011,'PO-90','N',"TX"));
      car_model_id.put(1, new DetailClass(1022,'PO-90','Y',"LA"));
  
      car_model_id.put(2, new DetailClass(1016,'PO-80','Y',"RE"));
      car_model_id.put(2, new DetailClass(1011,'PO-80','N',"GA"));
      car_model_id.put(2, new DetailClass(1022,'PO-80','N',"NY"));
  
     car_manufacturer_id.put((long) 501747, car_model_id);
  </code></pre>