content: package act.plugin;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  import act.app.ProjectLayoutProbe;
  
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;
  
  /**
   * Mark the extended class. This is used by plugin class which does not
   * extends a certain class directly.
   * <p>For example, suppose a plugin developer created a class
   * {@code MyProjLayoutProbe} extends {@link ProjectLayoutProbe},
   * the class could be sensed by Act directly; however if the developer decide
   * extend {@code MyProjLayoutProbe} and create another class
   * {@code MySubProjLayoutProbe} then this {@code Extends @Extends}
   * annotation needs to be used to mark on the new class. Otherwise, the plugin detector
   * will not be able to detect the second class that does not extends the
   * {@link ProjectLayoutProbe} class directly
   * </p>
   */
  @Retention(RetentionPolicy.CLASS)
  @Target(ElementType.TYPE)
  public @interface Extends {
      /**
       * Mark the class that the underline type will extends directly or
       * indirectly
       */
      Class<?> value();
  }
  