XML Attribute not "saved" in the pom.xml

<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/services/io.vertx.core.spi.VerticleFactory</resource></transformer>
</transformers>

public static Configuration getShadeConfiguration() {
    PluginElement manifestTransformer = ConfigurationElementBuilder.create()
        .setName("transformer")
        .addAttribute("implementation", "org.apache.maven.plugins.shade.resource.ManifestResourceTransformer")
        .setText("<manifestEntries>" +
            "<Main-Class>io.vertx.core.Launcher</Main-Class>" +
            "<Main-Verticle>${verticle.main}</Main-Verticle>" +
            "</manifestEntries>");

    PluginElement appendingTransformer = ConfigurationElementBuilder.create()
        .setName("transformer")
        .addAttribute("implementation", "org.apache.maven.plugins.shade.resource.AppendingTransformer")
        .setText("<resource>META-INF/services/io.vertx.core.spi.VerticleFactory</resource>");

    ConfigurationElement transformers = ConfigurationElementBuilder.create().setName("transformers")
        .addChild(manifestTransformer)
        .addChild(appendingTransformer);

    Configuration configuration = ConfigurationBuilder.create();
    configuration.addConfigurationElement(ConfigurationElementBuilder.create().setName("outputFile").setText("${project" +
        ".build.directory}/${project.artifactId}-${project.version}-fat.jar"));
    configuration.addConfigurationElement(transformers);
    return configuration;
  }

 builder.addExecution(ExecutionBuilder.create().addGoal("shade").setPhase("package").setId("package-fat-jar").setConfig(configuration));
pluginFacet.addPlugin(builder);

    <plugin>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.3</version>
        <executions>
          <execution>
            <id>package-fat-jar</id>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <outputFile>${project.build.directory}/${project.artifactId}-${project.version}-fat.jar</outputFile>
              <transformers>
                <transformer>
                  <manifestEntries>
                    <Main-Class>io.vertx.core.Launcher</Main-Class>
                    <Main-Verticle>${verticle.main}</Main-Verticle>
                  </manifestEntries>
                </transformer>
                <transformer>
                  <resource>META-INF/services/io.vertx.core.spi.VerticleFactory</resource>
                </transformer>
              </transformers>
            </configuration>
          </execution>
        </executions>
      </plugin>