code: @Override
    public WritableBuffer allocate(int capacityHint) {
      capacityHint = Math.min(MAX_BUFFER, Math.max(MIN_BUFFER, capacityHint));
      return new OkHttpWritableBuffer(new Buffer(), capacityHint);
    }
docs: For OkHttp we will often return a buffer smaller than the requested capacity as this is the
  mechanism for chunking a large GRPC message over many DATA frames.