title: Map is not being updated after put statement
body: <p>Ok so as the title says i do not really see why my map is not being updated. </p>
  
  <p>I have a "hotel" which has rooms. Each room can have a customer. Hotel rooms are populated at the very begining, and giving them Key (1-10) and Customer (which initially is null)</p>
  
  <pre><code>public class Hotel {
  
  public Map&lt;Integer, Room&gt; map = new HashMap&lt;&gt;();
  
  public static void main(String[] args) {
      new Hotel().run();
  }
  public void run() {
      // create rooms
      createRooms();
      // add customer 
      addCustmer(2, "Plastman");
  
      showRooms();
  
  }
  public void showRooms() {
      for (Map.Entry&lt;Integer, Room&gt; entry : map.entrySet()) {
          Integer roomNumber = entry.getKey();
          Room room = entry.getValue();
          System.out.println("Room: " + roomNumber + " Customer " + room.getCutomer() );
      }
  }
  public void addCustmer(Integer roomNumber, String customer) {
      // check if room is empty.
      Room room = map.get(roomNumber);
      if(room.getCutomer() == null || room.getCutomer().equals("")) {
          // room is vacant.
          System.out.println("Room is vacant. Adding customer: " + customer);
          map.put(roomNumber, new Room(customer));
      } else {
          // room is NOT vacant.
          System.out.println("Room is NOT vacant");
      }
  }
  private void createRooms() {          
      for(int i = 1; i &lt; 11; i ++) {
          map.put(i,new Room(""));
      }
  } 
  </code></pre>