Javadoc plugin config override not working in modular project

问题

I have a project with two generic parents: one for normal projects and one for modular projects (which extends the one for normal projects).

My project uses the modular parent pom and overrides the javadoc:jar execution by setting <show>private</show> instead of the default public as configured in the generic parent pom for normal projects.

However, the override is not honored, even though the effective-pom that it looks good to me.

I've an reproducible example case of this on Github:

• https://github.com/bbottema/javadoc-problem-case

Generic parent pom for normal projects:

<?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.bbottema</groupId>
    <artifactId>standard-project-parent</artifactId>
    <packaging>pom</packaging>
    <name>standard-project-parent</name>
    <version>1.0.11-SNAPSHOT</version>

    <properties>
        <java.version>1.7</java.version>
        <compiler.encoding>UTF-8</compiler.encoding>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <configuration>
                    <doclint>all,-missing</doclint>
                    <show>public</show>
                    <nohelp>true</nohelp>
                    <detectOfflineLinks>false</detectOfflineLinks>
                    <excludePackageNames>*.internal:*.internal.*:testutil:demo</excludePackageNames>
                    <quiet>true</quiet>
                    <failOnError>false</failOnError>
                </configuration>
                <executions>
                    <execution>
                        <id>jar</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                    <encoding>${compiler.encoding}</encoding>
                    <compilerArgument>-Xlint:all</compilerArgument>
                    <useIncrementalCompilation>false</useIncrementalCompilation>
                </configuration>
            </plugin>
        </plugins>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-javadoc-plugin</artifactId>
                    <version>3.1.1</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

Generic parent pom for modular projects:

<?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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>com.github.bbottema</groupId>
        <artifactId>standard-project-parent</artifactId>
        <version>1.0.11-SNAPSHOT</version>
    </parent>

    <artifactId>modular-project-parent</artifactId>
    <packaging>pom</packaging>
    <name>modular-project-parent</name>
    <version>1.0.12-SNAPSHOT</version>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <executions>
                    <execution>
                        <id>aggregate-jar</id>
                        <goals>
                            <goal>aggregate-jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Project pom:

<?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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>com.github.bbottema</groupId>
        <artifactId>modular-project-parent</artifactId>
        <version>1.0.12-SNAPSHOT</version>
    </parent>

    <artifactId>module-parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0.0-SNAPSHOT</version>
    <name>Master pom</name>

    <modules>
        <module>modules/module-a</module>
        <module>modules/module-b</module>
    </modules>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <executions>
                    <execution>
                        <id>jar</id>
                        <configuration>
                            <show>private</show>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Only if I set private in the generic parent pom for normal projects, will the generated javadoc contain private docs. Using JDK8. How do I fix this override? I was looking into combine.self with no luck unfortunately.

来源：https://stackoverflow.com/questions/59335821/javadoc-plugin-config-override-not-working-in-modular-project