@Override
  public Region getRegion() {
    return userRegionNameToShadowPRMap.size() == 1
        ? (Region) userRegionNameToShadowPRMap.values().toArray()[0] : null;
  }
This returns queueRegion if there is only one PartitionedRegion using the GatewaySender
Otherwise it returns null.
geode-core/src/main/java/org/apache/geode/internal/cache/wan/parallel/ParallelGatewaySenderQueue.java