@Override
  public void close() {
    Region<?, ?> r = getRegion();
    if (r != null && !r.isDestroyed()) {
      try {
        r.close();
      } catch (RegionDestroyedException ignored) {
      }
    }

  }
Initializes the <code>Region</code> backing this queue. The <code>Region</code>'s scope is
DISTRIBUTED_NO_ACK and mirror type is KEYS_VALUES and is set to overflow to disk based on the
<code>GatewayQueueAttributes</code>.

@param sender The GatewaySender <code>SerialGatewaySenderImpl</code>
@param listener The GemFire <code>CacheListener</code>. The <code>CacheListener</code> can be
       null.
geode-core/src/main/java/org/apache/geode/internal/cache/wan/serial/SerialGatewaySenderQueue.java