Add concise Javadocs for Spark DNS source and sink (Spark 3.5.x)

[Copilot]

Document the Spark 3.5.x DNS source/sink so behavior and options are clear when reading or writing DNS zones.

• Source/read path

  • Added class/method Javadocs for data source entry points, streaming source, offsets, RDD/partition classes, and schema conversion.
  • Clarified IXFR/AXFR transfer handling, offset semantics, and zone parameter mapping.

• Sink/write path

  • Documented sink provider, relation, batch/stream handlers, partition processor, and low-level DNS update client.
  • Clarified validation/normalization and grouping of updates by zone.

• Shared models/options

  • Added brief descriptions for common options, DNS record POJOs, actions, change factory, and IXFR delta structures.

Example (trimmed):

/**
 * Structured Streaming source that surfaces DNS zone transfers as Spark rows while
 * tracking per-zone offsets compatible with Spark 3.5.x.
 */
public class DnsStreamingSource implements Source { ... }

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• net
  • Triggering command: /usr/sbin/named /usr/sbin/named -u bind -g --detach --pid-file /run/containerd/io.containerd.runtime.v2.task/moby/321ac71dd69d32f1c01ee68c9ac4ba38b239176e59fb2a7e9f485a3afb54023b/083eb07149481d7b1c176fade99474fd0b68285ae1758c58faecf2c0f32c-C 321ac71dd69d32f1c01ee68c9ac4ba38b239176e59fb2a7e9f485a3afb54023b --log-format json --systemd-cgroup--version bash t-e9�� --root /var/run/docker/172.17.0.3 4/lib/jspawnhelp--dport 12207309d9.tmp.cgrep --log-format json 4/lib/jspawnhelper (dns block)
  • Triggering command: /usr/sbin/named /usr/sbin/named -u bind -g ! -i docker0 -j fdd03183181d05e98c9cd99319c6c229e47/log.json json --systemd-cgroup--root docker-entrypoin/var/run/docker/runtime-runc/moby poin�� k-dns/checkpoint/run/containerd/io.containerd.runtime.v2.task/moby/321ac71dd69d32f1c01ee68c9ac4b/usr/bin/containerd-shim-runc-v2 (dns block)
  • Triggering command: /usr/sbin/named /usr/sbin/named -u bind -g poin�� (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

make comments and docstrings for spark DNS data source and sink (Spark version 3.5.x) for all files under src/main/java. the result should be in a new PR

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.