@Override
  public CompletableFuture<List<ServerName>> listDecommissionedRegionServers() {
    return this.<List<ServerName>> newMasterCaller()
      .action((controller, stub) -> this.<ListDecommissionedRegionServersRequest,
        ListDecommissionedRegionServersResponse, List<ServerName>> call(controller, stub,
          ListDecommissionedRegionServersRequest.newBuilder().build(),
          (s, c, req, done) -> s.listDecommissionedRegionServers(c, req, done),
          resp -> resp.getServerNameList().stream().map(ProtobufUtil::toServerName)
            .collect(Collectors.toList())))
      .call();
  }
Compact the region at specific region server.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java