private long getOpenSeqNumForParentRegion(RegionInfo region) throws IOException {
    MasterFileSystem fs = master.getMasterFileSystem();
    long maxSeqId = WALSplitUtil.getMaxRegionSequenceId(master.getConfiguration(), region,
      fs::getFileSystem, fs::getWALFileSystem);
    return maxSeqId > 0 ? maxSeqId + 1 : HConstants.NO_SEQNUM;
  }
Queries META table for the passed region encoded name, delegating action upon results to the
{@code RegionStateVisitor} passed as second parameter.
@param regionEncodedName encoded name for the Region we want to query META for.
@param visitor           The {@code RegionStateVisitor} instance to react over the query
                         results.
@throws IOException If some error occurs while querying META or parsing results.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStateStore.java