The latest servers support retries on individual data partitions. This feature is useful when a cluster is migrating and partition(s) are missed or incomplete on the first scan attempt.
If the first scan attempt misses 2 of 4096 partitions, then only those 2 partitions are retried in the next scan attempt from the last key digest received for each respective partition. A higher default maxRetries is used because it's wasteful to invalidate all scan results because a single partition was missed.
public ScanPolicy()