Support Apache Flink 2.x (currently capped at Flink 1.19)

[joshmanis618-stack]

Problem

Sedona's Flink module is locked to Flink 1.x — 1.9.0 targets Flink 1.19, and the
latest dependency work (#2985) only moves to flink-table-planner_2.12 1.20.4,
still Flink 1.x and still Scala-suffixed. There's no path to run Sedona on Flink
2.x today.

This blocks teams standardizing on Flink 2.x — e.g. pipelines that need 2.x-era
Kafka source / deserialization APIs (Protobuf ingestion) can't drop below 2.0,
so Sedona's spatial functions are simply off the table. My use case is streaming
map-matching / spatial joins of vehicle positions against an indexed road network
— a spatial-index workload that doesn't reduce to point-level shapely calls.

Scope

The geometry core (sedona-common) is Flink-agnostic; the break is confined to
sedona-flink:

• Scala-free artifacts — sedona-flink_2.12 / flink-table-planner_2.12 →
  the unsuffixed Flink 2.x table artifacts.
• Removed legacy interfaces — SourceFunction / SinkFunction / SinkV1 are
  gone in 2.0; move to Source/Sink v2.
• Serialization — Geometry TypeInformation / serializer registration likely
  needs updating for Flink 2.x.
• Build — a Flink 2.x variant alongside the 1.x line.

Questions

1. Is Flink 2.x support already on anyone's radar / in progress?
2. Would a Flink-2.x compatibility module be accepted as a contribution (kept
   side-by-side with 1.x during transition), or is there a preferred shape first?

Happy to test against a real Flink 2.2 streaming workload if someone picks it up.

Environment

• Sedona 1.9.0 · Flink target 2.2.0 · streaming Table/DataStream, geospatial map-matching

[jiayuasu]

@joshmanis618-stack It will be great if you can contribute the support of Flink 2.X. If you don't have time, I am happy to give it a try.

I think, since this is a breaking change, we can put it in a major release (like Sedona 2.0). We plan to cut a minor release Sedona 1.9.1 in a few weeks. Then we can merge your change into the master.

[joshmanis618-stack]

@jiayuasu Thanks! I'd like to take a crack at it. Fair warning: I know Flink 2.x (running 2.2 in prod) but I'm new to Sedona's internals — I expect the TypeSerializer/TypeSerializerSnapshot migration and the table-planner-loader change to be where I need help. Would you be open to reviewing an early draft / pointing me at the gotchas? Happy to target master for the 2.0 line. If you and your team end up doing this faster than I can accomplish the work, don't wait up on me.

[jiayuasu]

@joshmanis618-stack Of course, I am happy to help. Feel free to ping me when you have questions!