Talk about send interface logic

[wolfstudy]

Is your feature request related to a problem? Please describe.

In Producer interface, Send is defined as follows:

Send(context.Context, *ProducerMessage) error

SendAsync(context.Context, *ProducerMessage, func(MessageID, *ProducerMessage, error))

In fact, when the pulsar client receives the sendReceipt, we don't assign a value to the ProducerMessage. The returned value is always nil.

Describe the solution you'd like

We can define the interface as follows:

Send(context.Context, *ProducerMessage) (MessageID, error)

SendAsync(context.Context, *ProducerMessage, func(MessageID,  error))

This way, on the one hand, it can be consistent with the Java client in the interface definition. On the other hand, we only need the msgID field. In this regard, if there is a place that is not considered comprehensive, please correct me.

[merlimat]

👍 SGTM. It was a frequently requested feature on the C++ based Go client.

[merlimat]

We should do this before stabilizing the API

[jiazhai]

seems already get a conclusion. would like to close this issue