Inheriting the version of an optional dependency-CodePudding

My company has 3 Maven projects organized as follows:

Project A depends on Project B.

Project B depends on Project C. (Project B has set Project C as an Optional dependency in their POM)

I am the owner of Project A. I would like to add Project C as a direct dependency in my POM. However, I do not want to be responsible for keeping the version of Project C up to date. Is there a way I can inherit the version of Project C specified in Project B's POM at all times?

CodePudding user response：

If you don't control project B, it's not possible, except possibly with some plugin hackery.

If you do control project B then you can declare a dependency management section in that project which you can additionally import into project A.

Project B POM

<dependencyManagement>
    <groupId>com.foo</groupId>
    <artifactId>project-c</artifactId>
    <version>1.2.3</version>
</dependencyManagement>
<dependencies>
    <dependency>
        <groupId>com.foo</groupId>
        <artifactId>project-c</artifactId>
        <!-- no need for version here, comes from dependencyManagement -->
        <optional>true</optional>
    </dependency>
</dependencies>

Project A POM

<properties>
    <!-- using a property isn't necessary, but ensures the
         POM import and dependency stay in sync -->
    <project.b.version>2.3.4</project.b.version>
</properties>
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.foo</groupId>
            <artifactId>project-b</artifactId>
            <version>${project.b.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
<dependencies>
    <dependency>
        <groupId>com.foo</groupId>
        <artifactId>project-b</artifactId>
        <version>${project.b.version}</version>
    </dependency>
    <dependency>
        <groupId>com.foo</groupId>
        <artifactId>project-c</artifactId>
        <!-- version is not necessary, imported from project-b's dependency management -->
    </dependency>
</dependencies>

This will mean Project A will default to Project B for all dependencies in B's dependency management section. I don't think there's a way to restrict it to just a specific one. I doubt you'll care but just something to be aware of.

Any versions that Project A defines, either in its own dependency management or directly in <dependencies>, will override any version brought in from Project B's dependency management.