code: public synchronized BigtableInstanceClient getInstanceAdminClient() throws IOException {
      if (instanceAdminClient == null) {
        ManagedChannel channel = createManagedPool(options.getAdminHost(), 1);
        instanceAdminClient = new BigtableInstanceGrpcClient(channel);
      }
      return instanceAdminClient;
    }
docs: <p>Getter for the field <code>instanceAdminClient</code>.</p>
  
  @return a {@link com.google.cloud.bigtable.grpc.BigtableInstanceClient} object.
  @throws java.io.IOException if any.