/lombok

name: lombok
description: >
  Always load this skill when you encounter any of these signals:
  • A build failure with "cannot find symbol" for Lombok-generated members (getX, setX, builder,
    toString, equals, hashCode, withX)
  • Source files annotated with @Data, @Getter, @Setter, @Slf4j, @Builder, @Value, @With,
    @NoArgsConstructor, @AllArgsConstructor, @RequiredArgsConstructor
  • A Maven or Gradle project that declares lombok as a dependency but fails to compile
    Lombok-produced symbols
  Covers the JDK 21+ annotation-processor gotcha that silently disables Lombok.
version: 0.1.0

Lombok

Lombok conventions and gotchas for Java projects. Language- and build-tool-specific conventions are covered by the `java` and `maven` skills.

Trigger: Lombok Not Running (JDK 21+)

Since JDK 21, javac no longer discovers annotation processors from the plain classpath — they must be declared explicitly. **Symptoms:**

• Compilation fails with `cannot find symbol` for methods that Lombok should generate:

`builder()`, `build()`, getters/setters (`getX()`/`setX()`), constructors (`@NoArgsConstructor`, `@AllArgsConstructor`, `@RequiredArgsConstructor`), `toString()`, `equals()`, `hashCode()`, `withX()` (`@With`), etc.

• The error location is a class annotated with `@Data`, `@Builder`, `@Value`, `@Getter`, ...
• Tests fail to compile calling `SomeLombokClass.builder()...` while the class itself compiled fine.

**Fix for Maven** — declare the processor explicitly in the compiler plugin (root pom, so all modules inherit it). Use a `${lombok.version}` property alongside an explicit property declaration; pin the actual value next to it:

<properties>
    <lombok.version>1.18.48</lombok.version>
</properties>
...
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>${lombok.version}</version>
    <scope>provided</scope>
</dependency>
...
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
        <proc>full</proc>
        <annotationProcessorPaths>
            <path>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${lombok.version}</version>
            </path>
        </annotationProcessorPaths>
    </configuration>
</plugin>

Check the latest version with the version-lookup tool before pinning; never guess versions. The lombok dependency itself stays `provided` scope — the `annotationProcessorPaths` entry is what makes javac actually run it.

**Fix for Gradle:**

dependencies {
    compileOnly 'org.projectlombok:lombok:1.18.48'
    annotationProcessor 'org.projectlombok:lombok:1.18.48'
}

Stale Build Output After Fixing the Processor

Maven's incremental compilation can keep stale `target/classes` files compiled *without* Lombok (missing `builder()` etc.), so the build keeps failing even after the pom is fixed. If the fix "doesn't work", delete the affected modules' `target/` directories once and rebuild. Do not assume the pom change is wrong — stale classes are the classic follow-up gotcha.

IDE Support

• **IntelliJ:** enable *Settings → Build → Compiler → Annotation Processors → Enable annotation

processing*, and install the Lombok plugin. Without it the IDE shows the same "cannot find symbol" errors even when Maven works.

• **Eclipse:** install the Lombok agent (lombok.jar) into the IDE.
• If the IDE and Maven disagree about lombok-generated symbols, suspect the IDE annotation

processing setting first.

Conventions

• Prefer `@Data` (or `@Value` for immutables) over hand-written boilerplate; add `@Builder` when

construction needs many optional fields.

• Keep the lombok dependency in `provided` scope — it must not end up in the packaged artifact.
• When adding other annotation processors (MapStruct, etc.), list them all in

`annotationProcessorPaths`; the entry replaces classpath discovery, it does not merge with it. MapStruct users also need `lombok-mapstruct-binding`.