private static int compareServerName(ServerName left, ServerName right) {
    if (left == null) {
      return right == null ? 0 : -1;
    } else if (right == null) {
      return +1;
    }
    return left.compareTo(right);
  }
Compare the region info.
@param other region plan you are comparing against
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/RegionPlan.java