docs: ByteBuffer[] writableNioBuffers(ByteBuf buf) {
      // Set the writer index to the capacity to guarantee that the returned NIO buffers will have
      // the capacity available.
      int readerIndex = buf.readerIndex();
      int writerIndex = buf.writerIndex();
      buf.readerIndex(writerIndex);
      buf.writerIndex(buf.capacity());
  
      try {
        return nioBuffers(buf, singleWriteBuffer);
      } finally {
        // Restore the writer index before returning.
        buf.readerIndex(readerIndex);
        buf.writerIndex(writerIndex);
      }
    }