public void setPosition(long oplogId, long offset) {
      this.oplogId = oplogId;
      this.offset = offset;
    }
Should only be used if this region has entries on disk that are not in memory. This currently
happens for overflow and for recovery when values are not recovered. The first iteration does a
normal iteration of the regionEntries. But if it finds an entry that is currently only on disk
it saves it in a list sorted by the location on disk. Once the regionEntries iterator has
nothing more to iterate it starts iterating over, in disk order, the entries on disk.
geode-core/src/main/java/org/apache/geode/internal/cache/DistributedRegion.java