{
  "stages": [
    {
      "name": "customers",
      "plugin": {
        "name": "File",
        "type": "batchsource",
        "properties": {
          "path": "hdfs://host:port/${customers_inputpath}" // ${customers_inputpath} will get replaced with the value of the 'customers_inputpath' runtime argument
        }
      }
    },
    {
      "name": "items",
      "plugin": {
        "name": "File",
        "type": "batchsource",
        "properties": {
          "path": "hdfs://host:port/${items_inputpath}" // ${items_inputpath} will get replaced with the value of the 'items_inputpath' runtime argument
        }
      }
    }
  ]
}

public interface Macro {

  /**
   * Get the value of the macro based on the context and arguments.
   *
   * @param arguments arguments to the macro
   * @param context the runtime context, which gives access to things runtime arguments.
   * @return the macro value
   */
  String getValue(@Nullable String arguments, RuntimeContext context) throws Exception;
}

@Beta
public interface PluginContext {

  /**
   * Gets the {@link PluginProperties} associated with the given plugin id.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @return the {@link PluginProperties}.
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  PluginProperties getPluginProperties(String pluginId);

  /**
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @param pluginProperties the {@link PluginProperties} for
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  void setPluginProperties(String pluginId, PluginProperties pluginProperties);

  /**
   * Loads and returns a plugin class as specified by the given plugin id.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @param <T> the class type of the plugin
   * @return the resulting plugin {@link Class}.
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  <T> Class<T> loadPluginClass(String pluginId);

  /**
   * Creates a new instance of a plugin. The instance returned will have the {@link PluginConfig} setup with
   * {@link PluginProperties} provided at the time when the
   * {@link PluginConfigurer#usePlugin(String, String, String, PluginProperties)} was called during the
   * program configuration time.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @param <T> the class type of the plugin
   * @return A new instance of the plugin being specified by the arguments
   *
   * @throws InstantiationException if failed create a new instance
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  <T> T newPluginInstance(String pluginId) throws InstantiationException;
}

package co.cask.cdap.api.plugin;
 
public final class Plugin {
  private final ArtifactId artifactId;
  private final PluginClass pluginClass;
  private PluginProperties properties;

  public Plugin(ArtifactId artifactId, PluginClass pluginClass, PluginProperties properties) {
    this.artifactId = artifactId;
    this.pluginClass = pluginClass;
    this.properties = properties;
  }

  /**
   * @return artifact id
   */
  public ArtifactId getArtifactId() {
    return artifactId;
  }

  /**
   * @return {@link PluginClass}
   */
  public PluginClass getPluginClass() {
    return pluginClass;
  }
  
  public void setPluginProperties(PluginProperties properties) {
    this.properties = properties;
  }

  /**
   * Returns the set of properties available when the plugin was created.
   */
  public PluginProperties getProperties() {
    return properties;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    Plugin that = (Plugin) o;
    return Objects.equals(artifactId, that.artifactId)
      && Objects.equals(pluginClass, that.pluginClass)
      && Objects.equals(properties, that.properties);
  }

  @Override
  public int hashCode() {
    return Objects.hash(artifactId, pluginClass, properties);
  }

  @Override
  public String toString() {
    return "Plugin{" +
      "artifactId=" + artifactId +
      ",pluginClass=" + pluginClass +
      ",properties=" + properties +
      '}';
  }
}