code: /*
   * Copyright © 2014-2017 EntIT Software LLC, a Micro Focus company (L.P.)
   *
   * 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.
   */
  package io.cloudslang.worker.execution.model;
  
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.Map;
  
  public class StepActionDataHolder {
  
      protected final List<Map<String, ?>> holder;
  
      public StepActionDataHolder() {
          this.holder = new ArrayList<>(4);
      }
  
      // Used by subclasses only
      private StepActionDataHolder(StepActionDataHolder stepActionDataHolder) {
          this.holder = stepActionDataHolder.holder;
      }
  
      public void addNotNullPartToHolder(Map<String, ?> actionDataPart) {
          this.holder.add(actionDataPart);
      }
  
      public void addNullablePartToHolder(Map<String, ?> actionDataPart) {
          if (actionDataPart != null) {
              this.holder.add(actionDataPart);
          }
      }
  
      public static class ReadonlyStepActionDataAccessor extends StepActionDataHolder {
  
          public ReadonlyStepActionDataAccessor(StepActionDataHolder stepActionDataHolder) {
              super(stepActionDataHolder);
          }
  
          public void addNotNullPartToHolder(Map<String, ?> actionDataPart) {
              throw new UnsupportedOperationException("Cannot mutate ReadonlyStepActionDataAccessor");
          }
  
          public void addNullablePartToHolder(Map<String, ?> actionDataPart) {
              throw new UnsupportedOperationException("Cannot mutate ReadonlyStepActionDataAccessor");
          }
  
          public Object getValue(String key) {
              // Reversed order traversal to simulate putAll
              ListIterator<Map<String, ?>> listIterator = this.holder.listIterator(this.holder.size());
              while (listIterator.hasPrevious()) {
                  Map<String, ?> element = listIterator.previous();
                  if (element.containsKey(key)) {
                      return element.get(key);
                  }
              }
              return null;
          }
      }
  }
  