[FLINK-40149][connector-http] Rename asyncPolling to async-polling

[bharathgunapati]

What is the purpose of the change

The HTTP lookup option for sync vs async polling is the only camelCase table
option in the connector (asyncPolling). All other options use kebab-case or
dotted keys (e.g. lookup-method, http.source.lookup.request.timeout).

This renames the canonical key to async-polling to align with Flink connector
naming conventions. The legacy asyncPolling key remains supported via
withDeprecatedKeys so existing DDL does not need to change.

No runtime behavior change: default remains false, and the option is already
read via ReadableConfig.get(ASYNC_POLLING).

Brief change log

• HttpLookupConnectorOptions.ASYNC_POLLING: canonical key async-polling,
  deprecated alias asyncPolling, description updated.
• Docs (en + zh): option table and examples updated to async-polling.
• Tests: parameterized factory and runtime tests cover both canonical and
  deprecated keys; ITCases updated to canonical key (mechanical).

Compatibility note

• Canonical key: async-polling
• Legacy key: asyncPolling still works via withDeprecatedKeys
• Default: false (unchanged)
• Migration: optional — existing DDL using asyncPolling continues to work;
  new configurations should use async-polling

Release note is on FLINK-40149.

Verifying this change

CI green on fork (Flink 2.2.0, JDK 11/17/21):
https://github.com/bharathgunapati/flink-connector-http/actions/runs/29353591657

Automated tests:

• HttpLookupTableSourceFactoryTest#shouldAcceptAsyncPollingAtFactory — factory
  accepts both async-polling and asyncPolling
• HttpLookupTableSourceTest#shouldCreateAsyncTableSourceWithAsyncPollingKey —
  runtime async path for both keys

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: no

Documentation

• Does this pull request introduce a new feature? no (consistency improvement)
• If yes, how is the feature documented? docs updated (en + zh)

[bharathgunapati]

Hi @davidradl — would you be able to review this when you have a moment?

Small consistency improvement (FLINK-40149): renames the lookup option asyncPolling → async-polling to match Flink kebab-case conventions. The legacy key still works via withDeprecatedKeys("asyncPolling"), so no DDL migration is required.

Scope: option key + docs + tests only — no runtime logic change (default remains false, still read via ReadableConfig).

Tests: parameterized factory and runtime tests cover both async-polling and the deprecated asyncPolling alias.

CI: green on my fork (Flink 2.2.0, JDK 11/17/21) — https://github.com/bharathgunapati/flink-connector-http/actions/runs/29353591657

Thanks!

[davidradl]

now we have release we cannot easily change a config name . We would need to deprecate but keep the old property and indicate people should use the new property name in preference. So we need to keep the docs for asyncPolling and still accept that property. We probably need some validation to reject configs with both keys set

[bharathgunapati]

Agreed with the review feedback — pushed 0b4cb59:

• Docs list both keys: async-polling (preferred) and asyncPolling (deprecated, still accepted)
• Factory rejects DDL that sets both keys (ValidationException)
• asyncPolling still works at runtime via withDeprecatedKeys — no behavior change for existing DDL