private HashMap<String, Long>
    fromTableServerTimestampProto(BackupProtos.TableServerTimestamp proto) {

    HashMap<String, Long> map = new HashMap<>();
    List<BackupProtos.ServerTimestamp> list = proto.getServerTimestampList();
    for (BackupProtos.ServerTimestamp st : list) {
      ServerName sn =
        org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil.toServerName(st.getServerName());
      map.put(sn.getHostname() + ":" + sn.getPort(), st.getTimestamp());
    }
    return map;
  }
Read the timestamp for each region server log after the last successful backup. Each table has
its own set of the timestamps. The info is stored for each table as a concatenated string of
rs->timestapmp
@param backupRoot root directory path to backup
@return the timestamp for each region server. key: tableName value:
        RegionServer,PreviousTimeStamp
@throws IOException exception
hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/impl/BackupSystemTable.java