@Override
  public CompletableFuture<Boolean> isMasterInMaintenanceMode() {
    return this.<Boolean> newMasterCaller()
      .action((controller, stub) -> this.<IsInMaintenanceModeRequest, IsInMaintenanceModeResponse,
        Boolean> call(controller, stub, IsInMaintenanceModeRequest.newBuilder().build(),
          (s, c, req, done) -> s.isMasterInMaintenanceMode(c, req, done),
          resp -> resp.getInMaintenanceMode()))
      .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