Force Maven use only first level dependencies

Question

I have a Maven Java project. I don't want my project dependencies to be satisfied by chance through a chain of subdependencies when compiling the project. It is OK for me when building the final war when maven must check all used dependencies and add necessary libs to the war, but when compiling the code I want to be sure that only direct dependencies are used. Why?

Let's say I have two dependencies:

<dependency>
    <groupId>com.package</groupId>
    <artifactId>module-1</artifactId>
</dependency>

<dependency>
    <groupId>com.package</groupId>
    <artifactId>module-2</artifactId>
</dependency>

For our project module-1 and module-2 serve completely different purposes, but somewhere in the dependency tree of module-2, module-1 is used. I delete module-1 dependency, but maven continue to build my project without compilation errors, because it resolves module-1 from module-2 sub-dependencies. This change goes unnoticed.

After sometime we decide to remove module-2, because we don't need it. Strange enough but we can not any more compile classes which were using imports from module-1 and which are not connected to module-2 logic.

This is a simple case, but in big project this can make quite a dependency mess.

Answer 1

You can use the Maven dependency plugin goal "dependency:analyze" to give you a report of all used dependencies which are not declared on the current module (included transitively). That way Maven will still use transitive dependencies (no way around that I guess), but you can force yourself via the plugin to make sure these are also declared. It will also warn you of unnecessary dependencies. Mind, the plugin analyzes the compiled classes. At times, you may need to configure the plugin, because occasionally it may not detect that a dependency is required at compile time but not at runtime, e.g. because a constant was inlined.