Apache Juneau cross-module / MockRestClient-driven integration test module.

This module is the reactor-cycle-bound integration residual of the TODO-160 test migration: it hosts the MockRestClient rest.* integration tests, the a.rttests cross-module round-trip suite, and the shared test infrastructure those depend on. It sits at the end of the reactor and depends on the modules it tests, so these tests cannot be co-located into the lower modules without creating Maven reactor cycles.

# Full clean build + all tests (recommended before a push)
python3 scripts/test.py --full

# Tests only (skip Maven compile)
python3 scripts/test.py --test-only

# Single module with Maven
mvn -f juneau-integration-tests/pom.xml test

JMH micro-benchmarks live in src/test/java/.../microbench/ and are excluded from the normal test run (Surefire only picks up **/*Test.class). Run them explicitly via the wrapper script or Maven directly.

Asserts the RestOpInvoker observability hot path — MetricsRecorder + TracerHook resolved to their NoOp singletons — allocates zero objects per invocation.

Run via script (recommended):

python3 scripts/microbench.py observability

The script compiles the benchmark, runs JMH with the GC allocation profiler (-prof gc), reads the JSON output, and asserts gc.alloc.rate.norm ≤ 8 bytes/op. Exit code 0 = pass.

Custom threshold:

python3 scripts/microbench.py observability --threshold 0

Run directly via Maven:

mvn -f juneau-integration-tests/pom.xml -Pmicrobench test-compile exec:java \
    -Dexec.mainClass=org.apache.juneau.marshall.microbench.observability.ObservabilityNoopBenchmark

JSON results are written to juneau-integration-tests/jmh-results/observability-YYYY-MM-DD.json.

The recorded baseline lives in perf-baseline.txt (project root) under the [observability] section. (The file was relocated from this module's directory to the project root by TODO-160, before the module was renamed from juneau-utest, so the per-module test-perf guard can track every reactor module.) To update after an intentional regression is accepted:

1. Run python3 scripts/microbench.py observability and note the gc.alloc.rate.norm value.
2. Edit the [observability] section in perf-baseline.txt manually.

1. Place the class in src/test/java/org/apache/juneau/microbench/<area>/.
2. Annotate with @Benchmark, @State, @BenchmarkMode, etc.
3. Add a public static void main(String[] args) using OptionsBuilder with forks(0) (required for the exec:java invocation to work).
4. Add a subcommand to scripts/microbench.py.
5. Document in this file and in perf-baseline.txt.