@Override
  protected WAL createRemoteWAL(RegionInfo region, FileSystem remoteFs, Path remoteWALDir,
    String prefix, String suffix) throws IOException {
    WALProvider provider = getWALProvider(region);
    if (provider instanceof AbstractWALProvider) {
      return ((AbstractWALProvider) provider).createRemoteWAL(region, remoteFs, remoteWALDir,
        prefix, suffix);
    }
    throw new IOException(
      provider.getClass().getSimpleName() + " does not support creating remote WAL");
  }
A group-provider mapping, make sure one-one rather than many-one mapping
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/RegionGroupingProvider.java