Maven assembly plugin: how to include provided dependencies of transitive dependencies

Question

It seems that including direct dependencies with provided scope is well understood. It also appears that including transitive dependencies with runtime scope is also easily accomplished.

But how can I include a dependency two levels of indirection away?

Example:

A --> B --> C

Where A depends on B (compile scope) and B depends on C (provided scope).

I want A to retrieve C (eg: download the jar locally), be it via assembly descriptor or maven-dependency-plugin:copy-dependencies or some other mechanism.

I've tried seemingly every combination of options for both of the aforementioned plugins. Neither approach covers this scenario. They both get B (even if B is changed to a provided dependency), and any compile scope dependencies of B, but not provided dependencies of B.

I suppose that I'm trying to do something similar to a shaded representation of my project but without unpacking dependencies.

Naturally I don't want to have to enumerate all of B's dependencies in A's pom - I'd like to retrieve (and then package) all dependencies implicitly and recursively.

Answer 1

You won't be able to do that. It is not a limitation of the maven-assembly-plugin, but the way Maven considers transitive dependencies. A transitive dependency that is of scope provided will be omitted, always (refer to this table in the documentation).

There is an open bug about this (MNG-2205) but I don't think it will be fixed anytime soon. This really is intended behaviour because provided dependencies, as per the name, as supposed to be provided at runtime.

Answer 2

Although Tunaki is quite right, I found a workable solution that's better than nothing, using a less well-known plugin (NOTE: only works with Maven <= 3.0.X)

This specifies two dependency blocks. The first pulls in normal compile deps including transitive, it's the same as using copy-dependencies. The second block specifically mentions B in addition to the normal pom dependency declaration (unfortunately, but at least both dependency mentions are in the same pom) and requests its provided deps:

        <plugin>
            <groupId>com.github.goldin</groupId>
            <artifactId>copy-maven-plugin</artifactId>
            <version>0.2.5</version>
            <executions>
                <execution>
                    <id>get-provided-dependencies</id>
                    <phase>generate-resources</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <resources>
                            <resource>
                                <targetPath>${project.build.directory}/lib</targetPath>
                                <dependencies>
                                    <dependency>
                                        <includeScope>compile</includeScope>
                                    </dependency>
                                    <dependency>
                                        <groupId>some.group</groupId>
                                        <artifactId>artifact_i_call_B</artifactId>
                                        <version>1.0</version>
                                        <includeScope>provided</includeScope>
                                    </dependency>
                                </dependencies>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
            </executions>
        </plugin>

Docs for this plugin may only exist in the archive at this point, not sure what happened to it: http://web.archive.org/web/20130826193436/http://evgeny-goldin.com/wiki/Copy-maven-plugin