private void initLowRedundancyBuckets() {
    for (BucketRollup b : buckets) {
      if (b != null && b.getRedundancy() >= 0 && b.getRedundancy() < requiredRedundancy) {
        lowRedundancyBuckets.add(b);
      }
    }
  }
Trigger the creation of a redundant bucket, potentially asynchronously.

This method will find the best node to create a redundant bucket and invoke the bucket operator
to create a bucket on that node. Because the bucket operator is asynchronous, the bucket may
not be created immediately, but the model will be updated regardless. Invoke
{@link #waitForOperations()} to wait for those operations to actually complete

@param bucket the bucket for which a redundant copy should be made
@param targetMember the member on which a redundant copy of a bucket should be made
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/rebalance/model/PartitionedRegionLoadModel.java