This tutorial walks through RBAC fundamentals, model classifications (RBAC0‑3), permission and user‑group concepts, then demonstrates practical Spring Security setups including in‑memory authentication, JWT integration, JSON‑based login, password encryption with BCrypt, and database‑backed authentication, providing complete code examples.
The article explains why adopting a message‑queue improves microservice decoupling and responsibility boundaries, then details the design of a pluggable Base‑MQ component—including @MQEventListener, MQEvent base class, configuration, and MQClient interface—followed by concrete implementations for RocketMQ, Kafka, Redis and RabbitMQ, an example event flow, and guidance for extending the framework.
The author recounts switching from Gson to Fastjson, encountering a date‑formatting bug that only appears on Linux due to an outdated Fastjson version, explores a circular‑reference $ref issue, and shares debugging steps, GitHub issue references, and practical fixes for reliable JSON serialization.
This article explains how to achieve seamless code updates for SpringBoot applications by allowing two processes to share the same port, detailing the underlying servlet container mechanics, the role of DispatcherServlet, and providing a complete Java implementation with step‑by‑step instructions and code samples.
This article explains how to implement gray (canary) release in a Spring Cloud micro‑service system using Nacos for service discovery, Spring Cloud Gateway filters, ThreadLocal gray flags, custom Ribbon load‑balancing rules, and configuration files to switch between production and gray versions.
This article walks through the One Billion Row Challenge, explaining the problem, baseline solution, and a series of performance optimizations—from JVM selection and parallel I/O to custom hash tables, unsafe memory access, and SIMD techniques—that shrink execution time from minutes to under two seconds.
This article explains the core concepts of connection‑pool technology, details the architectural choices behind HikariCP such as dual HikariPool instances, FastList, custom ConcurrentBag, ThreadLocal caching, and byte‑code generation, and walks through the key source code that makes the pool exceptionally fast.
This article demonstrates three methods for invoking external services in a Spring Boot application—using raw HttpClient, the RestTemplate utility, and Feign clients—providing code examples, configuration steps, and tips for handling headers and tokens.
This article clarifies how Inversion of Control (IoC) serves as a design pattern that hands control to an external container, while Dependency Injection (DI) is a concrete IoC implementation that automatically supplies required objects, detailing their definitions, purposes, implementations, and typical usage scenarios.
This article demonstrates how Java 8’s functional interfaces—such as Supplier, Consumer, Runnable, and Function—can replace repetitive if‑else statements for exception handling and branch logic, providing clear code examples, custom interfaces, and utility methods to simplify backend development.
JDK 23, the next non‑LTS release of the Java platform slated for September 17, introduces a suite of preview features—including scoped values, structured concurrency, flexible constructor bodies, implicit class and instance methods, module import declarations, Markdown Javadoc, vector API enhancements, and a default generational ZGC mode—while deprecating sun.misc.Unsafe memory‑access methods.
This article provides a comprehensive overview of Java's ConcurrentHashMap, explaining its purpose, underlying lock‑segmentation and CAS mechanisms in JDK 7 and JDK 8, demonstrating usage with sample code, and outlining scenarios where it delivers high‑performance thread‑safe map operations.
This article introduces JetCache, an open‑source distributed caching framework built on Spring and Redis, outlines its key features and typical scenarios, and provides step‑by‑step guidance for integrating JetCache into a SpringBoot application with configuration examples and sample code.
This article presents a detailed walkthrough of the TreeUtil class, demonstrating how to construct hierarchical tree structures from flat lists, define tree nodes in Java, perform generic and functional implementations of makeTree, traverse trees using pre‑order, level‑order and post‑order methods, flatten trees back to lists, and sort tree nodes recursively, all illustrated with complete code examples.
This article explains how SpringBoot interceptors work, demonstrates custom interceptor implementation, shows how misuse of ThreadLocal can cause memory leaks and OOM errors, and provides a fix by moving cleanup logic to afterCompletion, complete with code samples and performance screenshots.
The article explains the Disruptor—an intra‑process, lock‑free, array‑based queue that achieves millions of operations per second—by covering its core concepts, demo code, source‑code mechanics, performance optimizations such as pre‑allocation and false‑sharing avoidance, and real‑world Vivo iTheme applications with best‑practice tips.
In Spring Boot you can customize JSON request and response handling by annotating fields with @JsonSerialize/@JsonDeserialize, registering a global ObjectMapper module, adding a PropertyEditor via @ControllerAdvice, creating a custom HttpMessageConverter, or using AOP interception, selecting the approach that matches your project’s complexity.
This article explains how the LiteFlow rule engine enables Java developers to define, configure, and execute complex serial and parallel business workflows using XML/JSON/YAML rule files, various node components, data contexts, and runtime parameters, with hot‑deployment and integration examples for Spring Boot projects.
This article presents LeetCode problem 112 "Path Sum", detailing the problem statement, example inputs and outputs, constraints, a recursive analysis, and complete reference implementations in Java, C++, and Python for determining whether a root‑to‑leaf path equals a given target sum.
This article explains the different effects of placing a try‑catch block inside versus outside a for loop in Java, covering usage scenarios, performance impact, memory consumption, and practical recommendations for choosing the appropriate approach during development.
This article explains critical pitfalls, proper shutdown handling, event loss during startup, suitable business scenarios, reliability guarantees, and best‑practice patterns for employing Spring Event in high‑traffic backend systems, providing concrete code examples and operational recommendations.
This guide explains what Java Agents are, their core capabilities such as bytecode enhancement, performance monitoring, security checks, and debugging, and provides step‑by‑step instructions for implementing the premain method, creating a ClassFileTransformer, packaging the agent with Maven, and loading it both statically and dynamically.
This article introduces JarEditor, an IntelliJ IDEA plugin that lets developers modify class files and resources inside a JAR directly—eliminating the need to extract, decompile, recompile, and repackage—while detailing its features, usage steps, and underlying mechanisms.
This article explains how to implement asynchronous request handling in Spring Boot using four approaches—AsyncContext, Callable, WebAsyncTask, and DeferredResult—detailing their execution flow, configuration of thread pools, and scenarios where async processing improves throughput.
This article demonstrates how to identify long‑method and duplicated code smells in a Java curriculum‑display service and refactor the implementation using the Decorator pattern, providing clear component diagrams, full code examples, and a runnable demo that showcases flexible extensions for different course types.
The article explains the major changes in Hutool 6.0, including the shift of package names to org.dromara.hutool, extensive refactoring of utilities and the HTTP module, performance optimizations, and provides migration guidance and recommendations for developers considering the upgrade.
This article explains the concept of gray (canary) release, details the required Spring Boot, Spring Cloud and Nacos versions, describes core components such as Nacos, Spring Cloud Gateway, Ribbon and OpenFeign, and provides a complete code‑first implementation with filters, interceptors, custom load‑balancer rules and deployment instructions for demonstrating gray release scenarios.
When updating a SpringBoot application the old process must be stopped because the new one cannot bind to the same port, but by leveraging Tomcat's embedded container, ServletWebServerFactory, and dynamic port handling you can keep both processes alive and achieve zero‑downtime deployments.
The article explains that Spring no longer recommends @Autowired field injection, describes constructor‑based, setter‑based, and field‑based dependency injection types, illustrates each with code examples, and outlines the drawbacks of field injection such as immutability issues, SRP violations, and tight coupling to the container.
This article documents a production incident where multiple Spring Boot services each consumed around 12 GB of memory, explains how to diagnose the issue using jps and jmap, details default JVM heap size calculations, and provides recommendations for configuring JVM parameters to prevent excessive memory usage.
This article explains the challenges of multiple product logins, reviews traditional session mechanisms, discusses session sharing solutions in clustered environments, and presents a CAS‑based single sign‑on implementation with Java code examples, highlighting differences between CAS and OAuth2 for secure authentication.
This article shares the author's experience of redesigning a microservice using Domain‑Driven Design, detailing a standardized layered architecture, directory structure, model conversions, common pitfalls, and practical recommendations to improve code clarity and testing efficiency.
This article explains the internal architecture of Java's HashMap, covering its array of buckets, linked‑list handling of hash collisions, and the conversion to red‑black trees for high‑collision scenarios, supplemented with code examples and visual diagrams.
This article provides an in‑depth analysis of Spring Security 6.x architecture, explaining its filter‑chain design, authentication and authorization mechanisms, key components such as DelegatingFilterProxy, FilterChainProxy, SecurityFilterChain, and offers code examples and practical guidance for developers.
This article demonstrates how to efficiently insert 300,000 rows into a MySQL table by using MyBatis batch operations, JDBC batch processing, and various performance optimizations such as batch size tuning, transaction management, and connection pooling.
The article demonstrates how to mask sensitive Java backend data by using Hutool's DesensitizedUtil for common types and a custom @Desensitization annotation with a DesensitizationTypeEnum‑driven Jackson serializer (or Fastjson ValueFilter) to apply flexible masking rules during JSON serialization.
This article explains how using Spring's @Transactional annotation together with explicit locks can cause unexpected concurrency issues, demonstrates the problem with sample code, analyzes why the lock becomes ineffective, and presents solutions such as separating transactional methods, using programmatic transactions, or locking the entire transaction.
This article explains how an event‑center abstracts domain events, offers a clear architecture and powerful features, compares it with raw message‑queue solutions, and provides Java code examples to help backend engineers adopt a more maintainable, decoupled design.
Spring AI has added full support for OpenAI's structured output feature, enabling developers to define JSON schemas for AI responses, with example code showing how to configure prompts, response formats, and BeanOutputConverter for seamless JSON-to-Java bean conversion, plus Spring Boot starter configuration.
The article presents a lightweight gray‑release platform for e‑commerce, detailing its four‑module architecture, unified data‑type and predicate rule model, matcher implementations, stable bucket‑based traffic allocation, developer SDK and configuration APIs, as well as whitelist handling and non‑functional considerations for rapid, fine‑grained deployments.
RocketMQ stores messages in a sequential CommitLog while using a ConsumerQueue index for fast random access, and employs two looping threads—RebalanceService for load‑balancing queue assignments and PullMessageService for continuously pulling messages and dispatching them to user callbacks via a thread‑pooled consumer pipeline.
RabbitMQ is a lightweight, open‑source AMQP broker offering reliable, flexible routing, clustering, and multi‑protocol support; it can be installed via Homebrew, Windows installers, or source on CentOS, and, using the rabbitmq_delayed_message_exchange plugin, Spring Boot applications can configure custom exchanges, queues, and send delayed messages with an x‑delay header.
This article analyzes typical thread‑pool misuses that caused a production outage, explains why tasks may slow down under load, and provides concrete recommendations such as pagination, timeout handling, proper pool sizing, avoiding shared pools, ThreadLocal cleanup, and cautious use of parallel streams.
After integrating JaCoCo, a Java service threw a ClassCastException during order processing due to the synthetic $jacocoData boolean array, and the article details the root cause, code analysis, synthetic fields, JaCoCo probe insertion, and a robust fix using field.isSynthetic() filtering.
IntelliJ IDEA 2024.2 introduces a suite of developer‑focused enhancements—including instant Spring Data JPA queries, cron expression auto‑completion, GraalJS‑powered HTTP client, advanced log management, real‑time performance charts, and rich data‑format visualizers—designed to boost productivity for Java and Kotlin programmers.
This article dissects the Guava library to reveal how seven classic design patterns—Builder, Proxy, Immutable, Singleton, Decorator, Adapter, and Observer—are implemented in its core classes, providing clear code examples, step‑by‑step construction processes, and practical insights for Java developers.
Fast‑Retry is a high‑performance Java library that enables asynchronous, multi‑task retry with customizable logic, offering a scalable alternative to synchronous retry frameworks like Spring‑Retry and Guava‑Retry for handling massive workloads such as millions of user identity queries.
This article explains the concept of database connection pools, why they are needed, their core principles and runtime mechanisms, compares traditional direct connections with pooled connections, and reviews major Java pool implementations such as DBCP, C3P0, Druid and HikariCP along with configuration tips and best‑practice considerations.
This article details a Java ClassCastException caused by JaCoCo’s injected $jacocoData boolean array, explains how synthetic fields arise during bytecode instrumentation, analyzes the failing encryptObject method, and presents a fix by filtering synthetic fields using isSynthetic() to restore normal order processing.
The article compares token‑based authentication options for Java microservices—stateless JWTs, OAuth 2.0 with access and refresh tokens, a centralized API‑gateway authority, and internal service‑to‑service schemes—guiding readers on selecting the best approach according to security, scalability, and business needs.
This article introduces the Mall‑Swarm open‑source microservice e‑commerce system, outlines its 2024 video tutorial covering Spring Cloud, Kubernetes deployment, and the full tech stack, and explains how learners can access demos, study materials, and join the learning community.
This article introduces the most useful JDK 17 language enhancements—including text blocks, improved NullPointerException messages, records, switch expressions, private interface methods, pattern matching, collection factory methods, new String APIs, Stream API extensions, the modern HttpClient, JShell, direct java file execution, and the Z Garbage Collector—providing code examples and practical guidance for Java developers.
This article explains how to apply Domain‑Driven Design in a Java backend project, detailing the responsibilities of each layer—domain, infrastructure, application, adapter, client, and start—along with practical code examples for a work‑order system.
This article investigates the performance differences between Java’s ‘+’ operator and StringBuilder for both simple and looped string concatenations, presenting JUnit benchmark results that show ‘+’ is comparable for single concatenations but significantly slower in loops, and recommends using the appropriate method based on context.
This article demonstrates how to transform overly complex Spring Boot controllers—filled with repetitive validation, try‑catch blocks, and business logic—into clean, maintainable implementations by applying @Valid annotations, streamlined validation, and a centralized global exception handler.
The article explains why Spring discourages field injection, compares constructor, setter, and field injection types, provides Java code examples, and outlines the drawbacks of field injection such as immutability issues, SRP violations, container coupling, and hidden dependencies.
A 2023 survey of 663 Java professionals reveals a sharp decline in Oracle Java's market share, with 86% planning or already migrating to OpenJDK alternatives due to cost, licensing uncertainty, audit risk, and a preference for open‑source solutions, while highlighting migration timelines, satisfaction, and emerging pricing models.
This guide explains how to integrate JSON Schema validation into a Spring Boot application, covering dependency setup, schema definition, bean configuration, service implementation, controller handling, and testing with curl examples to ensure JSON payloads conform to the defined rules.
This article thoroughly explains OpenFeign’s core architecture, detailing its original Feign foundation, seven essential components, dynamic proxy generation, HTTP call execution flow, and how Spring Cloud seamlessly integrates and configures OpenFeign through annotations, factories, and property-based settings.
This guide explains three common ways to output MyBatis SQL statements and their execution times—using simple configuration logging, a custom MyBatis interceptor plugin, and the third‑party p6spy library—along with code examples and practical considerations for development and production environments.
This article explains how to quickly test MyBatis SQL statements by bypassing the Spring container, using a minimal MyBatis configuration, adding support for PageHelper pagination and MyBatis‑Plus plugins, and provides code examples and a plugin recommendation for efficient backend development.
This article provides an in‑depth overview of Sentinel, the Alibaba‑developed traffic‑control component for microservices, covering its core concepts, flow‑control algorithms, circuit‑breaking rules, real‑time monitoring features, and practical usage examples with Maven and code snippets.
This article introduces Java 8 Stream API, explains its functional style similar to SQL, and demonstrates how to process PO objects using filter, map, sorted, forEach, collect, statistics, and parallelStream operations with complete code examples.
Spring Boot can emulate SPI plug‑in extensions by using native Java ServiceLoader, conditional bean registration with @ConditionalOnClass/@ConditionalOnProperty, custom FactoryBean implementations, or programmatic BeanDefinitionRegistryPostProcessor registration, each enabling dynamic service loading based on configuration or runtime conditions.
This article describes a Java‑based asynchronous processing SDK that leverages Spring AOP, transactional event listeners, Kafka, XXL‑Job, and MySQL to provide non‑intrusive, reliable, and eventually consistent background execution of business methods while preserving transaction integrity and offering configurable retry and compensation strategies.
A recent Azul survey of 663 Java professionals shows that 86% of Oracle Java users are migrating to OpenJDK due to high costs, licensing uncertainty, audit risks, and a preference for open‑source alternatives, with most migrations completing within a year and delivering significant cost savings.
This article explains the concepts of Test‑Driven Development (TDD), Unit Test‑Driven Development (UTDD), Acceptance Test‑Driven Development (ATDD) and Behavior‑Driven Development (BDD), discusses why TDD is not dead, compares the three approaches, and provides a step‑by‑step Java implementation with code samples, testing workflow, and refactoring guidance.
This article explains how to use Redis for distributed locking, discusses the shortcomings of naive implementations, and presents robust solutions including identifier verification, Lua scripting for atomicity, the RedLock algorithm, and Redisson's advanced features such as re‑entrancy and watchdog mechanisms.
This article explains what memory leaks are in Java, outlines common causes such as unreleased resources, static collections, misuse of ThreadLocal, improper variable scope, inner‑class references and off‑heap memory, and provides practical solutions and best‑practice recommendations to avoid them.
The guide explains how to protect a Java core module deployed on user servers by integrating ProGuard for bytecode obfuscation, Xjar for JAR encryption, and ClassFinal for class‑file encryption, providing Maven plugin configurations, startup commands, and verification that the combined approach renders decompiled code empty or unreadable.
This article details the design, architecture, and Java implementation of a WebSocket‑based backend that enables real‑time, multi‑player quiz battles, covering entity definitions, message handling, matchmaking logic, error handling, game flow, and supporting utilities such as Redis‑based state management.
This article explains the Java Proxy design pattern, its three core roles, static and dynamic implementation approaches, provides a complete code example, and outlines typical scenarios where proxies improve access control, functionality, and system decoupling.
This article introduces Lock4j, a Java distributed lock library supporting RedisTemplate, Redisson, and Zookeeper, walks through its key features, dependency setup, configuration, annotation attributes, simple and advanced usage examples, and demonstrates custom executors, key builders, and failure strategies for robust concurrency control.
This article explains how to design a unified JSON response format for backend services, define clear status‑code conventions, encapsulate results in a Result class, and use a custom @ResponseResult annotation together with a ResponseBodyAdvice interceptor to automatically wrap controller outputs, improving readability and error handling.
Java 8’s functional interfaces, such as Supplier, Consumer, Runnable, and Function, let developers replace verbose if‑else chains with concise lambda‑based constructs, improving readability by encapsulating conditional logic in custom @FunctionalInterface definitions that handle true/false branches, exceptions, and optional values.
This article details the step‑by‑step process of switching a SpringBoot‑MyBatisPlus application from MySQL to PostgreSQL, covering driver integration, JDBC configuration changes, numerous SQL and type‑conversion pitfalls, and provides ready‑to‑run PostgreSQL scripts for bulk column adjustments and default values.
A market study reveals that rising Oracle Java subscription costs are driving many users to migrate to OpenJDK, and this guide explains the reasons behind the shift and provides step‑by‑step instructions for removing Oracle JDK and installing OpenJDK.
This article explains how to quickly develop an AI‑native application using Spring AI, covering core features such as chat models, prompt templates, function calling, structured output, image generation, embedding, vector stores, and Retrieval‑Augmented Generation (RAG), and provides end‑to‑end Java code examples for building a simple AI‑driven service.
Spring AOP cannot advise non‑bean, static, or internally‑called methods, limiting its use for the Diagnose framework, so the article proposes a Java Agent that transforms bytecode at startup, bypasses proxy constraints, and reliably intercepts private, static, and self‑invoked methods across separate class loaders.
This article introduces JDFrame/SDFrame, a JVM‑level DataFrame library that provides a more semantic and concise API for Java 8 stream operations, demonstrates how to add the Maven dependency, shows practical examples for filtering, grouping, sorting, joining, pagination, and explains the differences between the mutable JDFrame and the immutable SDFrame.
This article presents fourteen actionable techniques for improving Java backend code quality, including using configuration files, Lombok's @RequiredArgsConstructor, modular design, exception handling, reducing unnecessary database calls, avoiding null returns, simplifying if‑else logic, minimizing controller logic, leveraging IDE features, reading source code, applying design patterns, embracing new knowledge, mastering fundamentals, and efficiently checking element existence, supplemented with concrete code examples.
The latest update of the Cool Request IDEA plugin introduces a powerful Trace function that automatically records execution times for any method—including Spring @Scheduled and xxl‑job tasks—offers customizable latency coloring, MyBatis SQL timing, call‑count indicators, and scriptable environment variables for seamless token handling and JSON parsing.
The article demonstrates how to transform overly complex Spring Boot controllers—filled with repetitive validation and business logic—into clean, maintainable code by using @Valid annotations, concise validation rules, and a centralized exception handler, effectively halving the code size and improving readability.
This article explains how to leverage Java 8's @FunctionalInterface, including Supplier, Consumer, Runnable, and Function, to eliminate repetitive if…else branches, handle exceptions, and simplify branch logic with concise lambda‑based utilities.
This article provides a detailed tutorial on database sharding (分库分表), covering concepts, common sharding strategies, a step‑by‑step MyCAT configuration, Java JDBC implementation, and key considerations such as data distribution, complexity, transaction handling, and development cost.
This guide explains why Kafka message backlogs occur, how to diagnose bugs, optimize consumer logic, and use temporary topics for emergency scaling, while emphasizing monitoring, alerts, and proper offset handling to keep your streaming system healthy.
This article provides a comprehensive, code‑first guide to the most common design patterns—including Strategy, Simple Factory, Singleton, Proxy, Factory Method, Observer, Template Method and Adapter—explaining their concepts, real‑world use cases, and complete Java implementations with Spring Boot integration.
This article explains the JVM memory architecture, object lifecycle, young and old generation garbage‑collection mechanisms, tuning goals such as low latency, high throughput and large heap, and provides practical advice on monitoring, common memory‑related problems, and choosing appropriate collectors for different application scenarios.
This article explains why SpringBoot's default @EnableScheduling runs tasks sequentially with noticeable delays, analyzes the underlying single‑threaded scheduler, and provides multiple solutions—including thread‑pool configuration, asynchronous execution, custom executors, and distributed locks—to achieve reliable and scalable scheduled jobs.
This article explains how to refactor Spring MVC controller layers by introducing a unified response wrapper, handling String conversion issues with ResponseBodyAdvice, applying JSR‑303 validation for request parameters, creating custom validation annotations, and implementing custom exceptions with a global exception handler to produce clean, maintainable backend code.
This article describes a business approval scenario where a company name entered by a business user must be checked for duplicates, and explains how to implement fuzzy matching using MySQL RegExp, tokenization with IKAnalyzer, and Java service code to extract, preprocess, match, and rank results by relevance.
This article explains how to build a clean, maintainable Controller layer in Spring by separating responsibilities, unifying response structures, applying global response wrapping, leveraging JSR‑303 validation for parameters, creating custom validation rules, and handling exceptions uniformly, all illustrated with practical Java code examples.
This article explains the fundamentals and key characteristics of Remote Procedure Call (RPC), outlines common use cases and popular frameworks, and then walks through the design and implementation of a simple custom RPC system—including a bespoke binary protocol, client‑side proxy generation, serialization, Netty‑based encoding/decoding, server‑side request handling, and result delivery—using Java and Netty.
This article explains how Spring 3.0's pure annotation development simplifies bean configuration, demonstrates defining beans with @Component, managing bean scopes, performing various injection techniques, reading properties files, and integrating MyBatis, providing complete code examples and best‑practice tips for backend Java developers.
This article explains what MyBatis second‑level cache is, why it’s needed, how to configure it globally and per‑mapper, the underlying CachingExecutor mechanism, and typical scenarios where enabling the cache can dramatically reduce database load and speed up read‑heavy applications.
This article explains how to protect Java backend code deployed on user servers by applying ProGuard, Xjar, and ClassFinal for JAR obfuscation and encryption, detailing Maven configurations, startup commands, decompilation results, and best‑practice integration of both tools in a Spring Boot project.
This article walks through the author's practical research on integrating WebSocket in Spring Boot, detailing step‑by‑step configurations for Javax, WebMVC, and WebFlux, comparing their APIs, highlighting pitfalls, and providing concrete code snippets and cold‑knowledge tips for both server and client implementations.
The article presents a Java‑based scenario execution framework that leverages design patterns, annotations, enums and a generic factory to replace repetitive if/else branches with abstract scene interfaces and concrete implementations, enabling developers to add new business cases by simply creating a class and enum constant while the infrastructure automatically discovers and wires it, improving extensibility, readability and code quality.
This article examines the need for reliable HTTP retries in offline store applications, evaluates simple loop retries, explores Apache HttpClient's built‑in retry mechanism, and proposes a hybrid solution that combines customized HttpClient retry handling with asynchronous message‑queue retries to achieve high availability and eventual consistency.
This article explains why combining Lombok's @Data and @Builder annotations can remove the automatically generated no‑args constructor, demonstrates the resulting compilation errors, and provides two practical solutions using @Tolerate or a combination of @RequiredArgsConstructor and @NoArgsConstructor, while also describing Lombok's annotation‑processing mechanism.
