[Feature] Upgrade programing language to Java 17

[wuchong]

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• I searched in the issues and found nothing similar.

Motivation

Currently, the default programming language of Fluss is still Java 8. We would like to upgrade the programming language used in this project to Java 17. This upgrade will provide several benefits, including using the latest version of spotless, Google Java Format, and dependencies, and using new language features, and long-term support.

However, we can't directly upgrade to Java 17, because most Flink users are still using Java 8 (Flink 2.0 turns to default Java 11), this requires Fluss release client/connector jars in Java 8 or Java 11 to be compatible with Flink.

Solution

Therefore, this is going to be a long work, and I would break it down into several phases:

Phase 1

Upgrade the local development environment to Java 17, but still compile and release the project in Java 8.

• CI build test on Java 8 with spotless skipped and compile checks on Java 17 #204
• Allow project to build with Java 17 and 21 #114 (default local language to Java 17)

Phase 2

Release for Java 8 & 11 & 17.

• CI build test on Java 8 & 11 & 17
• Release binary distribution for only Java 17
• Release maven artifacts for both Java 8 and Java 11 and Java 17

Phase 3

Drop the legacy Java version support for Flink. Upgrade the language level to Java 17.

• Remove CI build for Java 8 and Java 11

Anything else?

No response

Willingness to contribute

• I'm willing to submit a PR!

[simonsssu]

Just one comment for phase-1, some new features like Pattern Matching for switch in JDK17 may be involved in local dev environment while compile and release will fail with jdk8.