Why no bulk Arrow→Parquet write API in Java? How to avoid row-by-row RecordConsumer + optimize?

### Describe the usage question you have. Please include as many useful details as possible.

I have ~ 20KB objects that I need to write to Parquet efficiently from Java.
In C++, C#, and Python there's a direct/bulk Arrow-Parquet write (e.g. WriteTable / write_table) that avoids row-by-row iteration, but in Java I only see row-by-row paths via RecordConsumer or internal/unstable column writers.
Questions:
1. Is there a supported bulk/columnar Arrow-Parquet write API in Java (e.g, VectorSchemaRoot
→ Parquet) that avoids row-by-row calls?
2. If not, why is Java limited to row-by-row writes today? Any roadmap for feature parity with C++/Python/C#?
3. For now, what's the recommended optimization path to write 20KB objects at high throughput from Java (without JNI), or is JNI/Dataset the recommended route?
4. Any best practices (batch sizing, encodings, writer settings) to mitigate the row-by-row overhead?

Thanks

### Component(s)

_No response_

まず、issue で挙げられている Java の書き込みパス、特に RecordConsumer、内部のカラムライター、VectorSchemaRoot を確認し、次にそれらを C++、C#、Python 向けに説明されている bulk API と比較します。サポートされている bulk Java パスが存在するかどうかを文書化し、現在の制限または roadmap を説明し、JNI を使わない推奨最適化経路を特定できれば完了です。

索引モデルが issue の本文から書いたものです。