Program: 89003
Project: 89003
Buggy source:
/** 
 * Merge a list of configurations into a new configuration.
 * @param configurations - list of configurations.
 * @param debugger - debugger instance.
 * @return Merged configuration.
 */
public static Configuration fromMultiple(List<Configuration> configurations,Debugger debugger){
  if (configurations == null)   return null;
 else   if (configurations.size() == 0)   return null;
 else   if (configurations.size() == 1)   return configurations.get(0);
  Configuration copy=null;
  for (  Configuration config : configurations) {
    if (copy == null) {
      copy=new Configuration(debugger,config.actionTypes);
    }
    copy.experienceDrop.putAll(config.experienceDrop);
    copy.playerDeathDrop.putAll(config.playerDeathDrop);
    copy.playerRewards.putAll(config.playerRewards);
    copy.levelingRate.putAll(config.levelingRate);
    mergeActions(copy.actionRewards,config.actionRewards);
    mergeActions(copy.complexRewards,config.complexRewards);
    if (config.defaultRewardsDisabled != DEFAULT_DISABLE_REWARDS)     copy.defaultRewardsDisabled=config.defaultRewardsDisabled;
    if (config.maximumEnchantLevel != DEFAULT_MAXIMUM_ENCHANT_LEVEL)     copy.maximumEnchantLevel=config.maximumEnchantLevel;
    if (config.maximumBookcaseCount != DEFAULT_MAXIMUM_BOOKCASE_COUNT)     copy.maximumBookcaseCount=config.maximumBookcaseCount;
    if (config.scanRadiusSetting != DEFAULT_SCAN_RADIUS)     copy.scanRadiusSetting=config.scanRadiusSetting;
    if (config.economyItemWorth != DEFAULT_ECONOMY_WORTH)     copy.economyItemWorth=config.economyItemWorth;
    if (!ObjectUtils.equals(config.economyDropItem,DEFAULT_ECONOMY_DROP))     copy.economyDropItem=config.economyDropItem;
    if (copy.messageQueue == null || !isStandardQueue(config.messageQueue))     copy.messageQueue=config.messageQueue;
    copy.rewardProvider=config.rewardProvider;
    copy.channelProvider=config.channelProvider;
    copy.parameterProviders=config.parameterProviders;
    copy.itemParser=config.itemParser;
    copy.mobParser=config.mobParser;
    copy.actionParser=config.actionParser;
    copy.playerParser=config.playerParser;
    copy.multiplier*=config.multiplier;
  }
  return new Configuration(copy,copy.multiplier);
}

Fixed version (ground truth):
/** 
 * Merge a list of configurations into a new configuration.
 * @param configurations - list of configurations.
 * @param debugger - debugger instance.
 * @return Merged configuration.
 */
public static Configuration fromMultiple(List<Configuration> configurations,Debugger debugger){
  if (configurations == null)   return null;
 else   if (configurations.size() == 0)   return null;
 else   if (configurations.size() == 1)   return configurations.get(0);
  Configuration copy=null;
  for (  Configuration config : configurations) {
    if (copy == null) {
      copy=new Configuration(debugger,config.actionTypes);
    }
    copy.experienceDrop.putAll(config.experienceDrop);
    copy.playerDeathDrop.putAll(config.playerDeathDrop);
    copy.playerRewards.putAll(config.playerRewards);
    copy.levelingRate.putAll(config.levelingRate);
    mergeActions(copy.actionRewards,config.actionRewards);
    mergeActions(copy.complexRewards,config.complexRewards);
    if (config.hadConfiguration(DISABLE_REWARDS_SETTING))     copy.defaultRewardsDisabled=config.defaultRewardsDisabled;
    if (config.hadConfiguration(MAXIMUM_ENCHANT_LEVEL_SETTING))     copy.maximumEnchantLevel=config.maximumEnchantLevel;
    if (config.hadConfiguration(MAXIMUM_BOOKCASE_COUNT_SETTING))     copy.maximumBookcaseCount=config.maximumBookcaseCount;
    if (config.hadConfiguration(VIRTUAL_SCAN_RADIUS_SETTING))     copy.scanRadiusSetting=config.scanRadiusSetting;
    if (config.hadConfiguration(ECONOMY_WORTH_SETTING))     copy.economyItemWorth=config.economyItemWorth;
    if (config.hadConfiguration(ECONOMY_DROPS_SETTING))     copy.economyDropItem=config.economyDropItem;
    if (copy.messageQueue == null || config.hadConfiguration(MESSAGE_MAX_RATE_SETTING))     copy.messageQueue=config.messageQueue;
    if (copy.rewardProvider == null || config.hadConfiguration(REWARD_TYPE_SETTING))     copy.rewardProvider=config.rewardProvider;
    if (copy.channelProvider == null || config.hadConfiguration(DEFAULT_CHANNELS_SETTING))     copy.channelProvider=config.channelProvider;
    copy.parameterProviders=config.parameterProviders;
    copy.itemParser=config.itemParser;
    copy.mobParser=config.mobParser;
    copy.actionParser=config.actionParser;
    copy.playerParser=config.playerParser;
    copy.multiplier*=config.multiplier;
  }
  return new Configuration(copy,copy.multiplier);
}