feat(java): improve Java 21 idiomatics

[davideme]

Summary

• Replace .collect(Collectors.toList()) with .toList() (Java 16+) across service and repository layers
• Use pattern matching for instanceof in LampEntity.equals() (Java 16+)
• Add LampNotFoundException with @ControllerAdvice handler for explicit 404 responses
• Change LampService.findById() to return Optional<Lamp> instead of nullable
• Change LampService.update()/delete() to throw LampNotFoundException instead of returning null/false
• Remove all @SuppressWarnings("unchecked"), unsafe double-cast patterns, and try/catch blocks from controller — exceptions now handled centrally by GlobalExceptionHandler

Closes #352

Test plan

• All 110 unit tests pass (mvn test)
• Spotless formatting check passes (mvn spotless:check)
• Checkstyle passes with 0 violations
• JaCoCo coverage checks met (>80% line, >75% branch)
• New LampNotFoundExceptionTest covers exception class
• Updated GlobalExceptionHandlerUnitTest covers 404 handler
• Controller tests updated to verify Optional/exception-based flow

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR modernizes the Java lamp API implementation by adopting newer Java idioms (e.g., Stream#toList(), pattern matching for instanceof), and by making “not found” behavior explicit via LampNotFoundException + centralized @ControllerAdvice handling, while shifting service APIs away from nullable/boolean sentinel returns.

Changes:

• Updated LampService to return Optional<Lamp> from findById() and to throw LampNotFoundException from update() / delete() instead of returning null/false.
• Introduced LampNotFoundException and added a GlobalExceptionHandler mapping to HTTP 404 responses.
• Replaced Collectors.toList() with toList() and updated unit/controller tests to reflect Optional/exception flows.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/java/src/test/java/org/openapitools/service/LampServiceTest.java	Updates service tests for Optional return type and exception-based update/delete behavior.
src/java/src/test/java/org/openapitools/exception/LampNotFoundExceptionTest.java	Adds unit coverage for the new exception message and ID retention.
src/java/src/test/java/org/openapitools/exception/GlobalExceptionHandlerUnitTest.java	Adds unit test coverage for the new 404 handler.
src/java/src/test/java/org/openapitools/controller/LampsControllerTest.java	Updates controller tests for Optional-based get flow and exception-based update/delete 404s.
src/java/src/main/java/org/openapitools/service/LampService.java	Shifts to Optional for findById, throws LampNotFoundException for update/delete, and uses toList().
src/java/src/main/java/org/openapitools/repository/impl/InMemoryLampRepository.java	Replaces Collectors.toList() with toList() in in-memory queries.
src/java/src/main/java/org/openapitools/exception/LampNotFoundException.java	Adds a dedicated domain exception carrying the missing lamp ID.
src/java/src/main/java/org/openapitools/exception/GlobalExceptionHandler.java	Adds @ExceptionHandler mapping LampNotFoundException to 404 responses.
src/java/src/main/java/org/openapitools/entity/LampEntity.java	Uses pattern matching for instanceof in equals().
src/java/src/main/java/org/openapitools/controller/LampsController.java	Removes local try/catch + unchecked casts; relies on centralized exception handling and Optional/exception-based flow.

[Copilot]

CompletableFuture.supplyAsync(...) is used without an explicit executor, which will run these request handlers on ForkJoinPool.commonPool(). That can create uncontrolled concurrency and lose request-scoped context (logging MDC, security context), and it diverges from the generated LampsApi defaults which use Runnable::run (synchronous). Prefer returning CompletableFuture.completedFuture(...) (since the logic is synchronous) or pass Runnable::run / a Spring-managed executor explicitly so request processing stays on the container thread pool.