@Override
  public CompletableFuture<Void> stopRegionServer(ServerName serverName) {
    StopServerRequest request = RequestConverter
      .buildStopServerRequest("Called by admin client " + this.connection.toString());
    return this.<Void> newAdminCaller().priority(HIGH_QOS)
      .action((controller, stub) -> this.<StopServerRequest, StopServerResponse, Void> adminCall(
        controller, stub, request, (s, c, req, done) -> s.stopServer(controller, req, done),
        resp -> null))
      .serverName(serverName).call();
  }
Get the region info for the passed region name. The region name may be a full region name or
encoded region name. If the region does not found, then it'll throw an UnknownRegionException
wrapped by a {@link CompletableFuture}
@return region info, wrapped by a {@link CompletableFuture}
hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java