public String displayContent() {
    StringBuilder sb = new StringBuilder();
    for (PartitionedRegion prQ : userRegionNameToShadowPRMap.values()) {
      if (prQ != null && prQ.getDataStore() != null) {
        Set<BucketRegion> allLocalBuckets = prQ.getDataStore().getAllLocalBucketRegions();
        for (BucketRegion br : allLocalBuckets) {
          if (br.size() > 0) {
            sb.append("bucketId=" + br.getId() + ":" + br.keySet() + ";");
          }
        }
      }
    }
    return sb.toString();
  }
Take will choose a random BucketRegionQueue which is primary and will take the head element
from it.
geode-core/src/main/java/org/apache/geode/internal/cache/wan/parallel/ParallelGatewaySenderQueue.java