How to Resolve MapStruct\'s \'Unknown Property\' Error When Used with Lombok?

MapStruct and Lombok Compatibility Issue: Unknown Property in Result Type

Problem Statement:

When using both MapStruct and Lombok together, an error occurs stating "Unknown property" in the result type. This issue arises when MapStruct cannot find a property in the target DTO class due to Lombok annotations removing getters and setters.

Cause:

Maven is using the MapStruct processor but not the Lombok processor. The annotationProcessorPaths in the Maven configuration specifies which processors should be used.

Solution:

Option 1: Add Lombok Dependency to AnnotationProcessorPaths

Modify the Maven compiler plugin configuration to include both the Lombok and MapStruct annotation processors:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.6.1</version>
    <configuration>
        <source>${java.version}</source>
        <target>${java.version}</target>
        <annotationProcessorPaths>
            <path>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${org.projectlombok.version}</version>
            </path>
            <path>
                <groupId>org.mapstruct</groupId>
                <artifactId>mapstruct-processor</artifactId>
                <version>${org.mapstruct.version}</version>
            </path>
        </annotationProcessorPaths>
    </configuration>
</plugin>

For Lombok versions 1.18.16 and above, also add the lombok-mapstruct-binding dependency:

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok-mapstruct-binding</artifactId>
    <version>0.2.0</version>
</dependency>

Option 2: Add MapStruct Processor as Dependency

Add the mapstruct-processor dependency to your dependencies and remove the annotationProcessorPaths:

<dependencies>
    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct-processor</artifactId>
        <version>${org.mapstruct.version}</version>
    </dependency>

Additional Note:

To ensure annotation processing in IntelliJ, add the mapstruct-processor as a provided dependency due to a known issue (IDEA-150621).

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