maven-javadoc-plugin does not generate javadocs

Question

I have a project with the following structure:

parent
 |-api
 |-plugin (depends on api)

The project is build using the clean install package tasks from maven on the parent module. The JARs generate correctly but the javadocs don't. How can I fix this?

This is what my parent module's pom looks like:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>PluginLogger</groupId>
    <artifactId>parent</artifactId>
    <version>1.1</version>
    <packaging>pom</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

    <modules>
        <module>plugin</module>
        <module>api</module>
    </modules>

    // repositories and dependencies go here...

    <build>
        <defaultGoal>clean install package</defaultGoal>

        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-javadoc-plugin</artifactId>
                    <version>3.6.3</version>
                    <configuration>
                        <outputDirectory>${project.build.directory}/javadoc</outputDirectory>
                        <sourceFileIncludes>
                            <include>**/me/suprB/pluginlogger/api/**/*.java</include>
                        </sourceFileIncludes>
                    </configuration>
                    <executions>
                        <execution>
                            <id>attach-javadocs</id>
                            <phase>package</phase>
                            <goals>
                                <goal>aggregate</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

I just want to generate the Javadocs for the "api" module, not the "plugin" one.

Answer 1

I created a small POC with a similar structure you provided. Based on my findings I would like to suggest the following:

• Please do not use the trailing ** in the <include> tag
• use reportOutputDirectory and destDir configurations instead of outputDirectory
• In my opinion you should not use pluginManagement here, since the plugin is used only by the parent pom.

Sample Parent POM

This is the actual pom.xml for my PoC's parent module:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.github.tcsizmadia</groupId>
    <artifactId>maven-javadoc-sandbox</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <modules>
        <module>api</module>
        <module>plugin</module>
    </modules>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <version>3.6.3</version>
                <executions>
                    <execution>
                        <id>attach-javadocs</id>
                        <phase>package</phase>
                        <goals>
                            <goal>aggregate</goal>
                        </goals>
                        <configuration>
                            <sourceFileIncludes>
                                <sourceFileInclude>com/github/tcsizmadia/api/**</sourceFileInclude>
                            </sourceFileIncludes>
                            <reportOutputDirectory>${project.build.directory}</reportOutputDirectory>
                            <destDir>javadoc</destDir>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Directory tree after issuing mvn clean install on parent module:

├── javadoc
│   ├── com
│   │   └── github
│   │       └── tcsizmadia
│   │           └── api
│   │               └── class-use
│   ├── legal
│   ├── resources
│   └── script-dir
│       └── images
└── javadoc-bundle-options

As you can see, it does not contain any documentation from plugin module - just from the api, as you requested.