feat(sdk/java): Spring Boot starter, reactive hardening, examples, live integration

[ancongui]

Summary

A four-axis pass on the Java SDK requested by the user:

1. Worked examples in parity with the Python SDK -- 6 new classes under flydocs-examples/.
2. flydocs-spring-boot-starter autoconfig module -- one-line drop-in for any Boot 3.5.x app.
3. Deep reactive correctness audit + hardening -- AutoCloseable, opt-in retry, cleaner waitForCompletion, bounded Netty pool.
4. Live integration test against the running flydocs API -- 5 tag-gated tests proving end-to-end wire compatibility.

The SDK is now structured as a Maven multi-module under sdks/java/:

sdks/java/
├── pom.xml                          (parent, packaging=pom)
├── flydocs-sdk/                     (core reactive client)
├── flydocs-spring-boot-starter/     (autoconfig + properties)
└── flydocs-examples/                (runnable examples; not deployed)

What changed in the core (flydocs-sdk)

Change	Why
FlydocsClient + FlydocsClientAsync implement AutoCloseable	The Netty ConnectionProvider is owned by the client and released on close(). The starter wires this via destroyMethod="close".
Opt-in retry filter (Builder.maxAttempts(N).retryMinBackoff(d))	Transient 5xx + timeouts retry with exponential backoff + jitter; 4xx is never retried.
waitForCompletion rewritten on repeatWhenEmpty	One timeout subscriber, no nested-Mono chain, easier to reason about.
New builder knobs: maxConnections, pendingAcquireTimeout, maxInMemorySize	Bounded pool + caller-tunable buffer limits.
Removed redundant codec config	.codecs() + .exchangeStrategies() were both setting maxInMemorySize; consolidated.

What flydocs-spring-boot-starter does

flydocs:
  base-url: http://localhost:8400
  timeout: 60s
  max-attempts: 3
  webhook:
    hmac-secret: ${FLYDOCS_WEBHOOK_HMAC_SECRET}

@RestController
class Ctl {
  Ctl(FlydocsClientAsync flydocs) { /* autowired */ }
}

• @AutoConfiguration + @ConditionalOnClass(FlydocsClientAsync.class) + @ConditionalOnProperty("flydocs.base-url") -- only activates when the SDK is on the classpath AND the base URL is configured.
• @ConditionalOnMissingBean on every produced bean -- user @Bean overrides win.
• Bean destroyMethod="close" -- the Netty pool is released cleanly on context shutdown.
• WebhookVerifier only published when flydocs.webhook.hmac-secret is set.
• spring-boot-configuration-processor for IDE completion in application.yaml.
• Registered via META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports (Boot 3.x discovery).

Examples (1:1 with Python)

Class	Mirrors
FirstExtractionExample	01_first_extraction.py
TypedSchemaAndRulesExample	02_typed_schema_and_rules.py
AsyncJobWithWaitExample	03_async_job_with_wait.py
WebhookReceiverApplication	04_webhook_receiver_fastapi.py
ErrorHandlingExample	05_error_handling.py
SyncFacadeExample	06_sync_facade.py

Plus ExampleHelpers mirroring examples_helpers.py. maven.deploy.skip=true so the module is compile-checked but never published.

Live integration

flydocs-sdk/src/test/.../integration/LiveApiIntegrationTest -- @Tag("integration"), @EnabledIfEnvironmentVariable("FLYDOCS_BASE_URL"). 5 tests covering version, health, validate, listJobs, typed-404. Activate with:

FLYDOCS_BASE_URL=http://localhost:8400 \
  mvn -pl flydocs-sdk test -Dgroups=integration

Verified against a real running service before this PR (5/5 passing).

CI

.github/workflows/publish-sdks.yaml: versions:set now uses -DprocessAllModules=true so child versions track the parent on tag push. The reactor publishes flydocs-sdk and flydocs-spring-boot-starter; flydocs-examples is built (compile-check) but never deployed.

Test plan

• mvn verify from sdks/java: 48 unit + 5 starter = 53 passing, 5 integration cleanly skipped.
• FLYDOCS_BASE_URL=http://localhost:8400 mvn -pl flydocs-sdk test -Dgroups=integration: 5/5 passing against a live API.
• All 6 example classes compile.
• CLI smoke: mvn -pl flydocs-examples compile exec:java -Dexec.mainClass=... works for each example.