code: protected ManagedChannel createChannelPool(final String hostString, int count) throws IOException {
      Preconditions.checkState(!options.useGCJClient(),
          "Channel pools cannot be created when using google-cloud-java");
      ChannelPool.ChannelFactory channelFactory = new ChannelPool.ChannelFactory() {
        @Override
        public ManagedChannel create() throws IOException {
          return createNettyChannel(hostString, options, clientInterceptors);
        }
      };
      return createChannelPool(channelFactory, count);
    }
docs: Create a new {@link com.google.cloud.bigtable.grpc.io.ChannelPool}, with auth headers.
  
  @param hostString a {@link java.lang.String} object.
  @return a {@link com.google.cloud.bigtable.grpc.io.ChannelPool} object.
  @throws java.io.IOException if any.