how to use apache-maven-shade plugin to resovle multi dependency conflict

Question

Maven shade plugin is very powerful for resolving dependency conclict, but a situation I have is as follows:

myproject

• guava 31
• thridparty-dependency-1
  • guava18

I could relocate the guava 31 dependency and then the conflict will be resolved. And how about following situation:

myproject

• thirdparty-1
  • guava31
• thirdparty-2
  • guava18
• thirdparty-3
  • guava4

Or how about if there are more than two dependencies conflicting as the same dependency but with different versions?

If I use relocation, then thirdparty-1/guava31 will be relocated but the guava18 and guava4 still conflict.

I'm not sure how to handle this situation.

Answer 1

You need to de-conflict these across the whole project, not just for the shaded uber-jar.

Use Maven <exclusions> in the pom.xml declarationtion to achieve this.

For example:

    <dependency>
        <groupId>org.neo4j</groupId>
        <artifactId>neo4j</artifactId>
        <version>${neo4j.version}</version>
        <exclusions>
            <exclusion>
                <groupId>io.netty</groupId>
                <artifactId>netty-transport-native-epoll</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-transport-native-epoll</artifactId>
        <version>${netty.version}</version>
    </dependency>