code: public long getTotalBytesOnTiersOrDefault(
        java.lang.String key,
        long defaultValue) {
      if (key == null) { throw new java.lang.NullPointerException(); }
      java.util.Map<java.lang.String, java.lang.Long> map =
          internalGetTotalBytesOnTiers().getMap();
      return map.containsKey(key) ? map.get(key) : defaultValue;
    }
docs: <pre>
  * the map of total bytes on each tier
  </pre>
  
  <code>map&lt;string, int64&gt; totalBytesOnTiers = 3;</code>