maven-shade-plugin 如何添加本地jar

如何用maven-shade-plugin，添加本地的jar

 <dependencies>
    <dependency>
      <groupId>org.richard</groupId>
      <artifactId>my-jar</artifactId>
      <version>1.0</version>
      <scope>system</scope>
      <systemPath>${project.basedir}/lib/my-jar.jar</systemPath>
    </dependency>
  </dependencies>

<build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
              <finalName>xxx-jar-with-dependencies</finalName>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
     <resources>
      <resource>
        <targetPath>lib/</targetPath>
        <directory>lib/</directory>
        <includes>
          <include>**/my-jar.jar</include>
        </includes>
      </resource>
    </resources>
  </build>

但是这部分会报错：

descriptorRefs is not allowed here.

 <descriptorRefs>
     <descriptorRef>jar-with-dependencies</descriptorRef>
 </descriptorRefs>

---

<plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>xxx.xxx</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>