[Feature][Flink] Define FlinkTableJob and FlinkStreamTableJob Java base classes

[ocb3916]

What is the purpose of the change

Implements Phase 0.2 of the Scala removal plan (#4408).

Defines FlinkTableJob and FlinkStreamTableJob as the Java abstract base classes that will
eventually replace the Scala FlinkTableTrait and FlinkStreamTableTrait traits — for Table API
(batch) jobs and jobs that mix the DataStream API with the Table API, respectively. Both classes
live in the existing streampark-flink-shims-base module and follow the same
ready → handle → destroy lifecycle established by FlinkStreamingJob in sub-issue 0.1, so all
three "Job" base classes share a consistent shape.

Brief change log

• Add FlinkTableJob abstract class with lifecycle: ready → handle → destroy, exposing the
  underlying TableEnvironment via getTableEnv() (composition) instead of extending / mimicking
  the interface like the legacy trait did
• Add FlinkStreamTableJob abstract class with the same lifecycle, exposing both
  StreamExecutionEnvironment (getEnv()) and StreamTableEnvironment (getTableEnv()) via
  composition
• Add sql(String) / sql(String, Consumer<String>) on both classes, bridging to the existing
  Scala FlinkSqlExecutor.executeSql so the public API surface stays Scala-free
• Add markConvertedToDataStream() on FlinkStreamTableJob, replacing the legacy trait's
  automatic Table → DataStream conversion detection (no longer possible under composition) with
  an explicit call
• Place both classes under org.apache.streampark.flink.core.javaapi rather than the
  issue-specified org.apache.streampark.flink.core.java — see note below
• Add JUnit 5 tests for both classes verifying lifecycle order, getTableEnv()/getEnv()
  composition, SQL execution, and the markConvertedToDataStream() flag
• Extract shared lifecycle/logic to fix SonarCloud duplication warnings:
  • AbstractFlinkJob (package-private) — common ready → handle → execute → destroy lifecycle, sql(...), and app.name lookup shared by both job classes
  • FlinkJobSupport — SQL callback bridging (Java Consumer <-> Scala Function1)
  • JobTestParams — shared ParameterTool builder used by both test classes
• Replace System.out.println with SLF4J logging in both execute(...) overrides

A note on the package name

The issue body specifies org.apache.streampark.flink.core.java. That name breaks Scala
compilation of every sibling file in streampark-flink-shims-base that references
java.util/java.io/java.lang — a nested package literally named java shadows the real
java.* standard library for any Scala file sharing the enclosing package. Reproduced both ways
in a clean build:

• org.apache.streampark.flink.core.java → BUILD FAILURE, 33 errors, all java.util/java.io/
  java.lang unresolved in unrelated sibling .scala files
• org.apache.streampark.flink.core.javaapi → BUILD SUCCESS, no other files affected

Went with javaapi for this PR. Open to other naming suggestions if javaapi isn't preferred.

Design note: composition instead of full delegation

The legacy traits extend/mimic Flink's TableEnvironment / StreamTableEnvironment directly,
re-implementing ~40-50 delegate methods each (FlinkStreamTableTrait additionally needed a
$-prefix naming hack to avoid clashes between the two APIs). The new classes hold the
environment(s) as fields instead, exposed via getTableEnv() / getEnv(). This removes the
delegate boilerplate and the naming hack, and means the classes won't go stale as the Flink Table
API changes — but it is a breaking change for code that currently calls Table API methods
directly on a trait instance (e.g. job.sqlQuery(...) → job.getTableEnv().sqlQuery(...)).
Flagging for discussion since the Phase 11 migration guide will need to cover it.

Verifying this change

mvn test -pl streampark-flink/streampark-flink-shims/streampark-flink-shims-base

Tests run: 9, Failures: 0, Errors: 0

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

• The public API
• The web application
• The build system

Documentation

• Relates to issue [Proposal] Remove Scala from StreamPark — design and migration plan #4408
• Part of umbrella issue [Proposal] Remove Scala from StreamPark — design and migration plan #4408, sub-issue 0.2

[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[wolfboys]

Thank you for your valuable contribution.
After careful evaluation, we found that the current PR introduces significant changes compared with the existing implementation and may impact the original design and migration approach. To ensure a minimal, stable, and manageable migration process, the PMC has discussed and reviewed the proposal, and we have redefined the roadmap for removing Scala.

Currently, we plan to proceed with Stage 1 — Flink Core: 4445 , 4446 , 4447 , 4448 , migrating modules incrementally according to the proposed execution plan(Principle: no logic changes; migrate modules to Java with readable, idiomatic code). We kindly suggest following the steps outlined in the issue: flink core

Thanks again for your effort and contribution. We look forward to continuing the collaboration on this migration.