/**
 * Copyright 2015 StreamSets Inc.
 *
 * Licensed under the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */
package com.streamsets.pipeline.configurablestage;

import com.streamsets.pipeline.api.Stage;

import java.util.List;

public abstract class DStage<C extends Stage.Context> implements Stage<C> {
  private Stage<C> stage;

  public Stage<C> getStage() {
    return stage;
  }

  abstract Stage<C> createStage();

  @Override
  public final List<ConfigIssue> init(Info info, C context) {
    if(stage == null) {
      stage = createStage();
    }
    return stage.init(info, context);
  }

  @Override
  public final void destroy() {
    stage.destroy();
  }

}

@@ -1368,24 +1368,50 @@
 destroy() %7B%0A
+    if(stage != null) %7B%0A  
     stage.de
@@ -1419,15 +1419,21 @@
 troy();%0A
+    %7D%0A
   %7D%0A%0A%7D%0A

DStage.destroy can throw NullPointerException