code: public static boolean addBuffersToStream(ByteBuf[] buffers, OutputStream stream) {
      if (!sZeroCopySendSupported || !stream.getClass().equals(sBufferList.getDeclaringClass())) {
        return false;
      }
      try {
        if (sCurrent.get(stream) != null) {
          return false;
        }
        for (ByteBuf buffer : buffers) {
          Object nettyBuffer = sNettyWritableBufferConstructor.newInstance(buffer);
          List list = (List) sBufferList.get(stream);
          list.add(nettyBuffer);
          buffer.retain();
          sCurrent.set(stream, nettyBuffer);
        }
        return true;
      } catch (Exception e) {
        LOG.warn("Failed to add data buffer to stream: {}.", e.getMessage());
        return false;
      }
    }
docs: Add the given buffers directly to the gRPC output stream.
  
  @param buffers the buffers to be added
  @param stream the output stream
  @return whether the buffers are added successfully