#vulnerable code 
                             @Override
	public List<Feature> encodeFeatures(List<String> ids, List<Feature> features, SkLearnEncoder encoder){
		List<? extends Number> dataMin = getDataMin();
		List<? extends Number> dataMax = getDataMax();

		ClassDictUtil.checkSize(ids, features, dataMin, dataMax);

		InvalidValueTreatmentMethod invalidValueTreatment = DomainUtil.parseInvalidValueTreatment(getInvalidValueTreatment());

		InvalidValueDecorator invalidValueDecorator = new InvalidValueDecorator()
			.setInvalidValueTreatment(invalidValueTreatment);

		List<Feature> result = new ArrayList<>();

		for(int i = 0; i < features.size(); i++){
			WildcardFeature wildcardFeature = (WildcardFeature)features.get(i);

			ContinuousFeature continuousFeature = wildcardFeature.toContinuousFeature();

			Interval interval = new Interval(Interval.Closure.CLOSED_CLOSED)
				.setLeftMargin(ValueUtil.asDouble(dataMin.get(i)))
				.setRightMargin(ValueUtil.asDouble(dataMax.get(i)));

			ValidValueDecorator validValueDecorator = new ValidValueDecorator()
				.addIntervals(interval);

			encoder.addDecorator(continuousFeature.getName(), validValueDecorator);
			encoder.addDecorator(continuousFeature.getName(), invalidValueDecorator);

			result.add(continuousFeature);
		}

		return result;
	} 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             @Override
	public List<Feature> encodeFeatures(List<String> ids, List<Feature> features, SkLearnEncoder encoder){
		List<? extends Number> dataMin = getDataMin();
		List<? extends Number> dataMax = getDataMax();

		ClassDictUtil.checkSize(ids, features, dataMin, dataMax);

		List<Feature> result = new ArrayList<>();

		for(int i = 0; i < features.size(); i++){
			WildcardFeature wildcardFeature = (WildcardFeature)features.get(i);

			ContinuousFeature continuousFeature = wildcardFeature.toContinuousFeature();

			Interval interval = new Interval(Interval.Closure.CLOSED_CLOSED)
				.setLeftMargin(ValueUtil.asDouble(dataMin.get(i)))
				.setRightMargin(ValueUtil.asDouble(dataMax.get(i)));

			ValidValueDecorator validValueDecorator = new ValidValueDecorator()
				.addIntervals(interval);

			encoder.addDecorator(continuousFeature.getName(), validValueDecorator);

			result.add(continuousFeature);
		}

		return super.encodeFeatures(ids, result, encoder);
	}