Program: 166075
Project: 166075
Buggy source:
private void calculateFeatureType(List<Pair<DimensionDescriptor.DimletDescriptor,List<DimensionDescriptor.DimletDescriptor>>> dimlets,Random random){
  dimlets=extractType(DimletType.DIMLET_FEATURE,dimlets);
  if (dimlets.isEmpty()) {
    for (    Map.Entry<Integer,FeatureType> entry : DimletMapping.idToFeatureType.entrySet()) {
      if (random.nextFloat() < DimletConfiguration.randomFeatureChance) {
        actualRfCost+=calculateCostFactor(entry.getKey());
        featureTypes.add(entry.getValue());
        List<DimensionDescriptor.DimletDescriptor> modifiers=Collections.emptyList();
        dimlets.add(Pair.of(new DimensionDescriptor.DimletDescriptor(DimletType.DIMLET_FEATURE,entry.getKey()),modifiers));
      }
    }
  }
  Map<FeatureType,List<DimensionDescriptor.DimletDescriptor>> modifiersForFeature=new HashMap<FeatureType,List<DimensionDescriptor.DimletDescriptor>>();
  for (  Pair<DimensionDescriptor.DimletDescriptor,List<DimensionDescriptor.DimletDescriptor>> dimlet : dimlets) {
    FeatureType featureType=DimletMapping.idToFeatureType.get(dimlet.getLeft().getId());
    featureTypes.add(featureType);
    modifiersForFeature.put(featureType,dimlet.getRight());
  }
  if (featureTypes.contains(FeatureType.FEATURE_LAKES)) {
    List<Block> blocks=new ArrayList<Block>();
    List<Block> fluids=new ArrayList<Block>();
    getMaterialAndFluidModifiers(modifiersForFeature.get(FeatureType.FEATURE_LAKES),blocks,fluids);
    if (fluids.isEmpty()) {
      while (random.nextFloat() < DimletConfiguration.randomLakeFluidChance) {
        int id=DimletRandomizer.getRandomFluidBlock(random);
        actualRfCost+=calculateCostFactor(id);
        fluids.add(DimletMapping.idToFluid.get(id));
      }
    }
 else     if (fluids.size() == 1 && fluids.get(0) == null) {
      fluids.clear();
    }
    fluidsForLakes=fluids.toArray(new Block[fluids.size()]);
  }
 else {
    fluidsForLakes=new Block[0];
  }
  if (featureTypes.contains(FeatureType.FEATURE_OREGEN)) {
    List<Block> blocks=new ArrayList<Block>();
    List<Block> fluids=new ArrayList<Block>();
    getMaterialAndFluidModifiers(modifiersForFeature.get(FeatureType.FEATURE_OREGEN),blocks,fluids);
    if (blocks.isEmpty()) {
      while (random.nextFloat() < DimletConfiguration.randomOregenMaterialChance) {
        int id=DimletRandomizer.getRandomMaterialBlock(random,true);
        actualRfCost+=calculateCostFactor(id);
        blocks.add(DimletMapping.idToBlock.get(id));
      }
    }
 else     if (blocks.size() == 1 && blocks.get(0) == null) {
      blocks.clear();
    }
    extraOregen=blocks.toArray(new Block[blocks.size()]);
  }
 else {
    extraOregen=new Block[0];
  }
  tendrilBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_TENDRILS);
  sphereBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_SPHERES);
  canyonBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_CANYONS);
}

Fixed version (ground truth):
private void calculateFeatureType(List<Pair<DimensionDescriptor.DimletDescriptor,List<DimensionDescriptor.DimletDescriptor>>> dimlets,Random random){
  dimlets=extractType(DimletType.DIMLET_FEATURE,dimlets);
  if (dimlets.isEmpty()) {
    while (random.nextFloat() < DimletConfiguration.randomFeatureChance) {
      int id=DimletRandomizer.getRandomFeature(random,false);
      FeatureType featureType=DimletMapping.idToFeatureType.get(id);
      if (!featureTypes.contains(featureType)) {
        actualRfCost+=calculateCostFactor(id);
        featureTypes.add(featureType);
        List<DimensionDescriptor.DimletDescriptor> modifiers=Collections.emptyList();
        dimlets.add(Pair.of(new DimensionDescriptor.DimletDescriptor(DimletType.DIMLET_FEATURE,id),modifiers));
      }
    }
  }
  Map<FeatureType,List<DimensionDescriptor.DimletDescriptor>> modifiersForFeature=new HashMap<FeatureType,List<DimensionDescriptor.DimletDescriptor>>();
  for (  Pair<DimensionDescriptor.DimletDescriptor,List<DimensionDescriptor.DimletDescriptor>> dimlet : dimlets) {
    FeatureType featureType=DimletMapping.idToFeatureType.get(dimlet.getLeft().getId());
    featureTypes.add(featureType);
    modifiersForFeature.put(featureType,dimlet.getRight());
  }
  if (featureTypes.contains(FeatureType.FEATURE_LAKES)) {
    List<Block> blocks=new ArrayList<Block>();
    List<Block> fluids=new ArrayList<Block>();
    getMaterialAndFluidModifiers(modifiersForFeature.get(FeatureType.FEATURE_LAKES),blocks,fluids);
    if (fluids.isEmpty()) {
      while (random.nextFloat() < DimletConfiguration.randomLakeFluidChance) {
        int id=DimletRandomizer.getRandomFluidBlock(random);
        actualRfCost+=calculateCostFactor(id);
        fluids.add(DimletMapping.idToFluid.get(id));
      }
    }
 else     if (fluids.size() == 1 && fluids.get(0) == null) {
      fluids.clear();
    }
    fluidsForLakes=fluids.toArray(new Block[fluids.size()]);
  }
 else {
    fluidsForLakes=new Block[0];
  }
  if (featureTypes.contains(FeatureType.FEATURE_OREGEN)) {
    List<Block> blocks=new ArrayList<Block>();
    List<Block> fluids=new ArrayList<Block>();
    getMaterialAndFluidModifiers(modifiersForFeature.get(FeatureType.FEATURE_OREGEN),blocks,fluids);
    if (blocks.isEmpty()) {
      while (random.nextFloat() < DimletConfiguration.randomOregenMaterialChance) {
        int id=DimletRandomizer.getRandomMaterialBlock(random,true);
        actualRfCost+=calculateCostFactor(id);
        blocks.add(DimletMapping.idToBlock.get(id));
      }
    }
 else     if (blocks.size() == 1 && blocks.get(0) == null) {
      blocks.clear();
    }
    extraOregen=blocks.toArray(new Block[blocks.size()]);
  }
 else {
    extraOregen=new Block[0];
  }
  tendrilBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_TENDRILS);
  sphereBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_SPHERES);
  canyonBlock=getFeatureBlock(random,modifiersForFeature,FeatureType.FEATURE_CANYONS);
}