Add producer access mode examples for Java and C++ client.

[shibd]

Preview

Related issue

• https://github.com/apache/pulsar/wiki/PIP-68%3A-Exclusive-Producer
• [feature request] C++ client support producer access mode. pulsar-client-cpp#95

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[Anonymitaet]

Thanks for your contribution!

1. Soft reminder: do not forget the 2nd task commented in [feat] Support ExclusiveWithFencing producer access mode. pulsar-client-cpp#201 (comment)

2. Can you provide the code PR link ([feat] Support ExclusiveWithFencing producer access mode. pulsar-client-cpp#201) in the PR description? So that reviewers can have more context on the doc changes.

[shibd]

Soft reminder: do not forget the 2nd task commented in.

Hi, @Anonymitaet The structure of the current document(next) is very different from the previous document(2.11.x, 2.10.x, etc).

I'm not sure where I should add it. And for the CPP client, We don't seem to manage the version of its documentation.

[Anonymitaet]

@shibd many thanks for your technical guidance!

Summarized what we discussed just now:

TO-DO tasks:

1. Add a note indicating the versions for Java and C++ to NEXT.

2. Record an issue to see if any contributors would like to apply the same doc changes to legacy doc versions.

   Since this feature is available from 2.8.x, docs should be added from then as below.

   The location might not be perfect but it's the most relevant place.

• Java

• C++

But in this PR, we only add docs to NEXT due to limited time and resources.

Instead, we plan to open an issue to see if any contributors would like to apply the same changes to versioned docs.

==========

Record another note for further learning: one value of access mode is available from 2.10.x. That value is shown on the doc set ≥ 2.11.x, so we do not need to update the doc since it's accurate.