```xml
  <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <java.version>1.7</java.version>
      <ngrinder.core.version>3.4</ngrinder.core.version>
      <plugin.id>ngrinder-jvm-monitor-plugin</plugin.id>
      <plugin.class>org.ngrinder.pluginName.helloPlugin</plugin.class>
      <plugin.version>1.0.0</plugin.version>
      <plugin.provider>NAVER</plugin.provider>
      <plugin.dependencies />
  </properties>

  <build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-jar-plugin</artifactId>
              <version>2.4</version>
              <configuration>
                  <archive>
                      <manifestEntries>
                          <plugin-Id>${plugin.id}</plugin-Id>
                          <plugin-Class>${plugin.class}</plugin-Class>
                          <plugin-Version>${plugin.version}</plugin-Version>
                          <plugin-Provider>${plugin.provider}</plugin-Provider>
                          <plugin-Dependencies>${plugin.dependencies}</plugin-Dependencies>
                      </manifestEntries>
                  </archive>
              </configuration>
          </plugin>
      </plugins>
  </build>
```

```java
  public class NetworkOverFlow extends SpringPlugin {

    public NetworkOverFlow(PluginWrapper wrapper) {
      super(wrapper);
    }

    @Override
    protected ApplicationContext createApplicationContext() {
      return null;
    }

  }
```

- 내부 클레스로 ngrinder-core의 확장 포인터들 중에서 구현하고자 하는 코드를 구현 한 후 @Extension 어노테이션을 주어 PF4J 컴파일시에 인덱스 될수 있도록 해준다.
```java
    @Extension
    public static class NetworkOverFlowExtension implements OnTestSamplingRunnable {

        @Override
        public User loadUser(final String userId) {
            ....
        }

    }
```

- 인덱싱된 파일 정보는 아래 경로에서 확인 가능 하다. loadPlugins시 해당 정보를 참고하여 load가 된다.

```
target/classes/META-INF/extensions.idx
```

- pf4j-spring의 SpringExtensionFactory를 상속받아 ngrinder의 ApplicationContext를 주입하여 사용하였다.

```java
      pf4j-spring -  SpringExtensionFactory
      .......
      @Override
      public Object create(Class<?> extensionClass) {
          Object extension = createWithoutSpring(extensionClass);
          if (autowire && extension != null) {
              // test for SpringBean
              PluginWrapper pluginWrapper = pluginManager.whichPlugin(extensionClass);
              if (pluginWrapper != null) {
                  Plugin plugin = pluginWrapper.getPlugin();
                  if (plugin instanceof SpringPlugin) {
                      // autowire
                      ApplicationContext pluginContext = ((SpringPlugin) plugin).getApplicationContext();
                      pluginContext.getAutowireCapableBeanFactory().autowireBean(extension);
                  }
              }
          }

          return extension;
      }
      ......
```

    아래는 Override 해준 코드이다.

```java
  @Component
  public class NGrinderSpringExtensionFactory extends SpringExtensionFactory {

    private final PluginManager pluginManager;

    @Autowired
    private ApplicationContext applicationContext;

    @Autowired
    public NGrinderSpringExtensionFactory(PluginManager pluginManager) {
    	super(pluginManager);
    	this.pluginManager = pluginManager;
    }

    protected void setApplicationContext(ApplicationContext applicationContext) {
    	this.applicationContext = applicationContext;
    }

    @Override
    public Object create(Class<?> extensionClass) {
    	Object extension = createWithoutSpring(extensionClass);
    	if (extension != null) {
    		PluginWrapper pluginWrapper = pluginManager.whichPlugin(extensionClass);
    		if (pluginWrapper != null) {
            applicationContext.getAutowireCapableBeanFactory().autowireBean(extension);
    		}
    	}
    	return extension;
    }

  }
```

```java
  NGrinderServiceProviderExtensionFinder
  ....
  private final String EXTENSIONS_RESOURCE_PATH = "META-INF/extensions.idx";

  @Override
  public Map<String, Set<String>> readPluginsStorages() {
      log.debug("Reading extensions storages from plugins");
      Map<String, Set<String>> result = new LinkedHashMap<String, Set<String>>();

      List<PluginWrapper> plugins = pluginManager.getPlugins();
      for (PluginWrapper plugin : plugins) {
          String pluginId = plugin.getDescriptor().getPluginId();
          log.debug("Reading extensions storages for plugin '{}'", pluginId);
          final Set<String> bucket = new HashSet<String>();

          URL url = ((PluginClassLoader) plugin.getPluginClassLoader()).findResource(EXTENSIONS_RESOURCE_PATH);
          if (url != null) {
              Path extensionPath;
              if (url.toURI().getScheme().equals("jar")) {
                  FileSystem fileSystem = FileSystems.newFileSystem(url.toURI(), Collections.<String, Object>emptyMap());
                  extensionPath = fileSystem.getPath(EXTENSIONS_RESOURCE_PATH);
              } else {
                  extensionPath = Paths.get(url.toURI());
              }
              Files.walkFileTree(extensionPath, Collections.<FileVisitOption>emptySet(), 1, new SimpleFileVisitor<Path>() {

                  @Override
                  public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                      log.debug("Read '{}'", file);
                      Reader reader = Files.newBufferedReader(file, StandardCharsets.UTF_8);
                      ServiceProviderExtensionStorage.read(reader, bucket);
                      return FileVisitResult.CONTINUE;
                  }

              });
          } else {
              log.debug("Cannot find '{}'", EXTENSIONS_RESOURCE_PATH);
          }
        ....
```