public static void warmupRegion(final RpcController controller,
    final AdminService.BlockingInterface admin,
    final org.apache.hadoop.hbase.client.RegionInfo regionInfo) throws IOException {

    try {
      WarmupRegionRequest warmupRegionRequest =
        RequestConverter.buildWarmupRegionRequest(regionInfo);

      admin.warmupRegion(controller, warmupRegionRequest);
    } catch (ServiceException e) {
      throw getRemoteException(e);
    }
  }
A helper to warmup a region given a region name using admin protocol
hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java