Java SDK v1.2.0

New Features and Improvements

• Built on Rust SDK 2.0.1: The JNI layer (rust/jni/) now depends on
  databricks-zerobus-ingest-sdk = "2.0.1" (was 2.0.0). The Java-facing API
  surface (ZerobusSdk, ZerobusProtoStream, ZerobusJsonStream,
  ZerobusArrowStream, StreamConfigurationOptions,
  ArrowStreamConfigurationOptions) is unchanged.
• Arrow Flight promoted to Beta: ZerobusArrowStream /
  ArrowStreamConfigurationOptions and the surrounding documentation
  (README, examples) are no longer labelled experimental. The API is
  stabilising but may still change before reaching GA. (Mirrors the Rust
  SDK 2.0.1 promotion.)
• ArrowStreamConfigurationOptions: Added streamPausedMaxWaitTimeMs for the maximum time (milliseconds) to wait in the paused state during graceful close (-1 = full server duration, 0 = immediate recovery).
• Java SDK identifier on the wire: The SDK now reports itself as
  zerobus-sdk-java/<version> on the HTTP user-agent header (previously
  it inherited the Rust SDK identifier zerobus-sdk-rs/<rust-version>).
  Server-side telemetry can now distinguish Java clients from Rust clients.

Behavior Changes

• StreamConfigurationOptions.maxInflightRecords default raised from
  50_000 to 1_000_000 to match the Rust SDK 2.0.1 default. The Java
  wrapper previously hard-coded 50k while the Rust SDK quietly raised its
  default to 1M, so Java clients ran with a 20× lower in-flight ceiling
  than Rust clients. Callers who relied on the old cap can pin it back
  explicitly:

  StreamConfigurationOptions.builder()
      .setMaxInflightRecords(50_000)
      .build();

Documentation

• Updated ArrowIngestionExample.java to demonstrate all three IPC
  compression codecs end-to-end. Opens three streams in sequence (NONE,
  LZ4_FRAME, ZSTD), ingests 10 batches per stream, then
  waitForOffset + flush + close.
• Updated README.md, examples/README.md, examples/arrow/README.md,
  and Javadoc on ZerobusArrowStream / ArrowStreamConfigurationOptions
  / ZerobusSdk.createArrowStream to reflect the Beta promotion.
• Documented the JDK 9+ --add-opens=java.base/java.nio=... JVM flags
  required by arrow-memory-netty 17.x when using ZerobusArrowStream,
  in both the main README and the Arrow examples README.

Internal Changes

• maven-surefire-plugin now passes the required --add-opens flags so
  Arrow integration tests run cleanly on JDK 9+ without per-developer
  setup.
• Bumped zerobus-jni crate version from 1.1.1 to 1.2.0 (used by the
  Java SDK identifier embedded at compile time via CARGO_PKG_VERSION).