Maven and eclipse: a reliable way to add non-Maven or external jars to a project?

1) you can use system scope dependency

    <dependency>
        <groupId>test</groupId>
        <artifactId>x</artifactId>
        <version>1.0</version>
        <scope>system</scope>
        <systemPath>${basedir}/lib/x.jar</systemPath>
    </dependency>

2) you can copy your x.jar to local maven repository as

repository/test/x/1.0/x-1.0.jar

and add a dependency as

    <dependency>
        <groupId>test</groupId>
        <artifactId>x</artifactId>
        <version>1.0</version>
    </dependency>