GH-3511: Add JMH encoding benchmarks and fix parquet-benchmarks shaded jar

[iemejia]

Summary

Resolves #3511.

The parquet-benchmarks shaded jar built from current master is non-functional — it fails at runtime with RuntimeException: Unable to find the resource: /META-INF/BenchmarkList. This PR fixes that and adds 11 JMH benchmarks covering the encode/decode paths exercised by the open performance PRs, so reviewers can reproduce the reported numbers.

What's broken on master

parquet-benchmarks/pom.xml is missing two pieces of configuration:

• maven-compiler-plugin lacks the annotationProcessorPaths / annotationProcessors config for jmh-generator-annprocess, so the JMH annotation processor never runs and META-INF/BenchmarkList / META-INF/CompilerHints are never generated.
• maven-shade-plugin lacks AppendingTransformer entries for those two resources, so even if generated they would be dropped during shading.

Both problems are fixed in this PR.

Benchmarks added

11 new files in parquet-benchmarks/src/main/java/org/apache/parquet/benchmarks/:

Benchmark	Coverage
IntEncodingBenchmark	int encode/decode: PLAIN, DELTA_BINARY_PACKED, BYTE_STREAM_SPLIT, RLE, DICTIONARY
BinaryEncodingBenchmark	Binary write/read paths, parameterized on length and cardinality
ByteStreamSplitEncodingBenchmark / ByteStreamSplitDecodingBenchmark	BSS for float / double / int / long
FixedLenByteArrayEncodingBenchmark	FLBA encode/decode
FileReadBenchmark / FileWriteBenchmark	CPU-focused file-level benchmarks
RowGroupFlushBenchmark	Flush path
ConcurrentReadWriteBenchmark	Multi-threaded read/write throughput
BlackHoleOutputFile	OutputFile that discards bytes — isolates CPU from I/O
TestDataFactory	Shared data-generation utilities

Validation

After this PR, the shaded jar is runnable and registers 87 benchmarks:

$ ./mvnw clean package -pl parquet-benchmarks -DskipTests \
    -Dspotless.check.skip=true -Drat.skip=true -Djapicmp.skip=true
$ java -jar parquet-benchmarks/target/parquet-benchmarks.jar -l | wc -l
87

Sanity check — IntEncodingBenchmark.decodePlain reproduces the master baseline cited in #3493/#3494 (~91M ops/s on JDK 21, JMH 1.37, 3 warmup + 5 measurement iterations):

Benchmark                            (dataPattern)   Mode  Cnt         Score         Error  Units
IntEncodingBenchmark.decodePlain        SEQUENTIAL  thrpt    5  93528419.575 ± 1472148.214  ops/s
IntEncodingBenchmark.decodePlain            RANDOM  thrpt    5  90908523.483 ± 1978982.394  ops/s
IntEncodingBenchmark.decodePlain   LOW_CARDINALITY  thrpt    5  92672978.255 ± 2071927.851  ops/s
IntEncodingBenchmark.decodePlain  HIGH_CARDINALITY  thrpt    5  90770177.655 ± 2427904.955  ops/s

Out of scope (deferred)

Modernization of the existing ReadBenchmarks / WriteBenchmarks / NestedNullWritingBenchmarks (Hadoop-free LocalInputFile, parameterization, JMH-idiomatic state setup) is a separate concern and will be proposed in a follow-up PR.

Follow-up

Once this lands, each open perf PR (#3494, #3496, #3500, #3504, #3506, #3510) will be updated with a one-line "How to reproduce" snippet referencing the relevant *Benchmark class.