maven plugin api: @Paramerter using setters doesn't work

Question

I am writing a custom maven-plugin for my project. Following the instructions mentioned here https://maven.apache.org/guides/plugin/guide-java-plugin-development.html#using-setters I added a @Parameter using setters as shown below.

@Parameter(property = "destinationDirectory", defaultValue = "${project.build.directory}/generated-resources")
private String _destinationDirectory;
private Path dstDirRoot;

public void setDestinationDirectory(String destinationDirectory) {
    Path dstDir = Paths.get(destinationDirectory);
    if (dstDir.isAbsolute()) {
         this._destinationDirectory = dstDir.toString();
    } else {
         this._destinationDirectory = Paths.get(baseDir, dstDir.toString()).toString();
    }
    dstDirRoot = Paths.get(this._destinationDirectory);
}

Pom.xml entries on the usage side

<plugin>
    <groupId>com.me.maven</groupId>
    <artifactId>my-maven-plugin</artifactId>
    <version>${project.version}</version>
    <executions>
        <execution>
            <goals>
                <goal>run</goal>
            </goals>
            <phase>generate-resources</phase>
        </execution>
    </executions>
    <configuration>
         <destinationDirectory>${project.build.directory}/myDir</destinationDirectory>
    </configuration>
</plugin>

Now, I was expecting that during the plugin execution, it would call setDestinationDirectory method. But it doesn't. @Parameter(property="...") doesn't seem to have any impact.

Is this a bug? Or am I missing something?

Answer 1

From maven-plugin-plugin version 3.7.0 you can simply add @Parameter annotation on public setter methods.

You code can looks like:

@Parameter(...)
public void setDestinationDirectory(String destinationDirectory) {
...
}

You also need to define version of maven-plugin-plugin and maven-plugin-annotations dependency in your pom.xml - both should have the same version.

<project>

<properties>
  <maven-plugin-tools.version>3.7.1</maven-plugin-tools.version>
</properties>

<dependencies>
  <dependency>
    <groupId>org.apache.maven.plugin-tools</groupId>
    <artifactId>maven-plugin-annotations</artifactId>
    <scope>provided</scope>
    <version>${maven-plugin-tools.version</version>
  </dependency>
</dependencies>

<build>
  <pluginManagement>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-plugin-plugin</artifactId>
      <version>${maven-plugin-tools.version}</version>
      <executions>
        <execution>
          <id>help-mojo</id>
          <goals>
            <goal>helpmojo</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </pluginManagement>
</build>

</project>