Maven Proguard插件-“在类路径上找不到proguard.Proguard”错误

<build>
  <plugins>
    <plugin>
      <groupId>com.github.wvengen</groupId>
      <artifactId>proguard-maven-plugin</artifactId>
      <version>2.0.14</version>
      <executions>
        <execution>
          <phase>package</phase>
          <goals>
            <goal>proguard</goal>
          </goals>
        </execution>
      </executions>
      <configuration>
        <proguardVersion>6.2.2</proguardVersion>
        <obfuscate>true</obfuscate>
        <injar>${project.build.finalName}.jar</injar>
        <outjar>${project.build.finalName}-proguarded.jar</outjar>
        <options>
          <option>-keep public class com.example.MyClass</option>
        </options>
      </configuration>
    </plugin>
  </plugins>
</build>

<dependencies>
  <dependency>
    <groupId>net.sf.proguard</groupId>
    <artifactId>proguard-base</artifactId>
    <version>6.2.2</version>
    <scope>runtime</scope>
  </dependency>
</dependencies>