private RegionResult getResult(byte[] region) {
    RegionResult rs = results.get(region);
    if (rs == null) {
      rs = new RegionResult();
      results.put(region, rs);
    }
    return rs;
  }
Returns the exception for the region, if any. Null otherwise.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java