OncePerRequestFilter base class

Bucket4j for rate limiting

ConcurrentHashMap bucket storage

Bandwidth.classic + Refill.greedy

429 on rate limit exceeded

getRemoteAddr() for client IP

No direct X-Forwarded-For read

Request log fields

Structured log format in filter

Duration timing

ForwardedHeaderFilter guidance

SLF4J logger declaration

Constructor injection

@RestController + @RequestMapping

@Validated on controller

Paginated list return type

Pagination request params

CREATED status for POST

@Valid on request body

Java records for DTOs

Bean validation on DTO fields

@ControllerAdvice handler class

Validation exception handler

AccessDenied handler

Generic exception handler with log

RFC 7807 problem details config

Constructor injection in service

@Transactional on write methods

@Transactional(readOnly=true) on reads

@EnableCaching config annotation

@Cacheable usage

@CacheEvict usage

@EnableAsync config annotation

@Async with CompletableFuture

SLF4J logger declaration

Structured key=value log format

Exception as last log argument

JPA repository with @Query

Pagination with Sort