@Override
  public String toString() {
    return "KeyPrefixRegionSplitPolicy{" + "prefixLength=" + prefixLength + ", " + super.toString()
      + '}';
  }
A custom RegionSplitPolicy implementing a SplitPolicy that groups rows by a prefix of the row-key
This ensures that a region is not split "inside" a prefix of a row key. I.e. rows can be
co-located in a region by their prefix.
@deprecated since 3.0.0 and will be removed in 4.0.0. Use {@link RegionSplitRestriction},
            instead.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/KeyPrefixRegionSplitPolicy.java