feat(visualization): require the Filled Area Plot line group under its switch

[kz930]

What changes were proposed in this PR?

Turning on Split Plot by Line Group makes Line Group required, because code generation asserts it and the run ends on Line Group cannot be empty. The field is declared @JsonProperty(required = false) and carried no conditional constraint, so the property panel accepted the configuration and the error waited for the run. A field that is optional is exactly the one a user leaves behind.

The schema states the rule instead, in the conditional form the Sklearn text columns already use (#7643): required: ["lineGroup"] under facetColumn, so the panel refuses the configuration while it is being written. Conditional rather than a plain required, so a freshly dropped operator, whose switch is off, is not flagged for a field it has no use for.

The assertion stays as the last line of defence, and the two tests that pin it stay with it. Nothing about the generated Python changes.

One thing worth noting beyond the panel: a rule stated in the schema is one the tooling can read. Our translator's configuration generator fills a conditionally-required field from exactly this shape, which is how it fills the Sklearn text columns under Count Vectorizer; the assertion in Scala was invisible to it.

Any related issues, documentation, discussions?

Closes #8283. Same shape as #7643, which stated the Sklearn rule.

How was this PR tested?

FilledAreaPlotOpDescSpec gains an assertion on the generated schema: the line group is not unconditionally required, and the conditional rule requires it under the switch. Removing the annotation turns that test red. WorkflowOperator/test passes: 2517 tests.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Claude Opus 5)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @eugenegujing
  You can notify them by mentioning @eugenegujing in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.93%. Comparing base (50321e4) to head (0a0093a).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8285      +/-   ##
============================================
- Coverage     93.93%   93.93%   -0.01%     
  Complexity     4761     4761              
============================================
  Files          1191     1191              
  Lines         48308    48308              
  Branches       5377     5377              
============================================
- Hits          45378    45376       -2     
- Misses         1495     1497       +2     
  Partials       1435     1435              

Flag	Coverage Δ		*Carryforward flag
access-control-service	81.00% <ø> (ø)
agent-service	99.32% <ø> (ø)		Carriedforward from 50321e4
amber	90.00% <ø> (-0.02%)	⬇️
computing-unit-managing-service	73.67% <ø> (ø)
config-service	86.86% <ø> (ø)
file-service	87.91% <ø> (ø)
frontend	96.41% <ø> (ø)		Carriedforward from 50321e4
notebook-migration-service	79.31% <ø> (ø)
pyamber	98.87% <ø> (ø)		Carriedforward from 50321e4
workflow-compiling-service	77.19% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 2 better · 🔴 8 worse · ⚪ 5 noise (<±5%) · 0 without baseline

Compared against main 50321e4 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	357	0.218	25,644/47,613/47,613 us	🔴 +21.5% / 🔴 +222.0%
🔴	bs=100 sw=10 sl=64	778	0.475	124,562/152,087/152,087 us	🟢 -10.3% / 🔴 +50.7%
⚪	bs=1000 sw=10 sl=64	928	0.566	1,071,516/1,133,416/1,133,416 us	⚪ within ±5% / 🔴 -17.2%

Baseline details

Latest main 50321e4 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	357 tuples/sec	414 tuples/sec	844.57 tuples/sec	-13.8%	-57.7%
bs=10 sw=10 sl=64	MB/s	0.218 MB/s	0.252 MB/s	0.515 MB/s	-13.5%	-57.7%
bs=10 sw=10 sl=64	p50	25,644 us	21,114 us	11,837 us	+21.5%	+116.6%
bs=10 sw=10 sl=64	p95	47,613 us	39,607 us	14,788 us	+20.2%	+222.0%
bs=10 sw=10 sl=64	p99	47,613 us	39,607 us	17,651 us	+20.2%	+169.7%
bs=100 sw=10 sl=64	throughput	778 tuples/sec	835 tuples/sec	1,084 tuples/sec	-6.8%	-28.2%
bs=100 sw=10 sl=64	MB/s	0.475 MB/s	0.51 MB/s	0.662 MB/s	-6.9%	-28.2%
bs=100 sw=10 sl=64	p50	124,562 us	116,875 us	94,505 us	+6.6%	+31.8%
bs=100 sw=10 sl=64	p95	152,087 us	169,578 us	100,941 us	-10.3%	+50.7%
bs=100 sw=10 sl=64	p99	152,087 us	169,578 us	108,642 us	-10.3%	+40.0%
bs=1000 sw=10 sl=64	throughput	928 tuples/sec	933 tuples/sec	1,119 tuples/sec	-0.5%	-17.1%
bs=1000 sw=10 sl=64	MB/s	0.566 MB/s	0.569 MB/s	0.683 MB/s	-0.5%	-17.2%
bs=1000 sw=10 sl=64	p50	1,071,516 us	1,068,792 us	924,404 us	+0.3%	+15.9%
bs=1000 sw=10 sl=64	p95	1,133,416 us	1,163,516 us	967,785 us	-2.6%	+17.1%
bs=1000 sw=10 sl=64	p99	1,133,416 us	1,163,516 us	995,630 us	-2.6%	+13.8%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,560.79,200,128000,357,0.218,25643.99,47612.67,47612.67
1,100,10,64,20,2569.46,2000,1280000,778,0.475,124562.36,152087.29,152087.29
2,1000,10,64,20,21549.95,20000,12800000,928,0.566,1071516.38,1133416.14,1133416.14

[kz930]

/request-review @aglinxinyuan @carloea2