The `sandbox-perf` build has been failing for a while with the following
errors:
```
INFO: From Generating benchmark code for //ledger/sandbox-perf:sandbox-perf_codegen:
JMH benchmark generation: JMH Benchmark generator failed
JMH benchmark generation: Benchmark classes should not be final.
[com.digitalasset.platform.sandbox.perf.LargeTransactionBench]
JMH benchmark generation: The instantiated @State class cannot be abstract.
[com.digitalasset.platform.sandbox.perf.PerfBenchState]
```
However, these errors are ignored; running the benchmarks runs the
`AcsBench` benchmark and ignores the fact `LargeTransactionBench` and
`SimpleBench` failed to compile.
I've fixed the errors by making sure that classes are not final, and
that `SimpleBench` uses a concrete state class.
This also introduces a cheap patch to the Scala JMH Bazel rules that
makes sure they fail if there are any errors.
I'm not really sure how to patch the Bazel rules properly, but someone
else might have an idea. :-)
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CHANGELOG_END
Co-authored-by: Samir Talwar <samir.talwar@digitalasset.com>
