fix(spark): correct the CTAS claim on VortexSessionCatalog.createTable

[jackylee-ch]

Rationale for this change

The javadoc on createTable said Spark writes a CREATE TABLE ... AS SELECT result into the table this overload returns. It does not. DelegatingCatalogExtension sends the Column[] overload straight to the delegate, and that is the overload both supported Spark versions call — 3.5's CreateTableAsSelectExec directly, 4.1's via the TableInfo default. This override never runs; CTAS gets its Vortex table from the loadTable override instead.

Had it run it would have thrown: V2SessionCatalog.createTable returns null on its normal path, and asVortexTableIfVortex dereferenced the argument immediately.

What changes are included in this PR?

Tolerate null in asVortexTableIfVortex, and replace the javadoc claim with what actually happens.

• ./gradlew :vortex-spark_2.13:test --tests '…VortexSessionCatalogTest' --tests '…VortexSqlTest' — 10 pass
• same on :vortex-spark_2.12:test
• spotlessCheck (both variants) and javadoc — clean

VortexSessionCatalogTest already covers the managed-table lifecycle on both versions, which is the path CTAS actually takes.

What APIs are changed? Are there any user-facing changes?

None.

AI assistance

Prepared with agentic AI assistance. I verified the dispatch against the compiled DelegatingCatalogExtension, CreateTableAsSelectExec and V2SessionCatalog in both Spark versions rather than reasoning from the source I had.

[robert3005]

does this mean we can remove the override? I might have mixed up the version/feature matrix

[codspeed-hq]

Merging this PR will improve performance by 13.04%

⚡ 1 improved benchmark
✅ 1943 untouched benchmarks
⏩ 85 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	decompress[u64, (1000, 16)]	73.3 µs	64.9 µs	+13.04%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing jackylee-ch:spark-session-catalog-ctas-doc (125801a) with develop (4b37237)}

Footnotes

1. 85 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩