ValueReference<K, V> previous = entry.getValueReference();
      int weight = map.weigher.weigh(key, value);
      checkState(weight >= 0, "Weights must be non-negative");

      ValueReference<K, V> valueReference =
          map.valueStrength.referenceValue(this, entry, value, weight);
      entry.setValueReference(valueReference);
      recordWrite(entry, weight, now);
      previous.notifyNewValue(value);
    }

 * 
 * <tr><td width="20%"><code>smb1://angus/</code></td><td>
 * This references only a server. The behavior of some methods is different
 * in this context(e.g. you cannot <code>delete</code> a server) however
 * as you might expect the <code>list</code> method will list the available
 * shares on this server.
 * </td></tr>
 * 
 * <tr><td width="20%"><code>smb1://myworkgroup/</code></td><td>

      ValueReference<K, V> previous = entry.getValueReference();
      int weight = map.weigher.weigh(key, value);
      checkState(weight >= 0, "Weights must be non-negative");

      ValueReference<K, V> valueReference =
          map.valueStrength.referenceValue(this, entry, value, weight);
      entry.setValueReference(valueReference);
      recordWrite(entry, weight, now);
      previous.notifyNewValue(value);
    }