src/main/java/com/feedzai/fos/impl/weka/WekaManager.java
private void trainClassifier(int classIndex, Classifier classifier, Instances wekaInstances) throws FOSException {
        wekaInstances.setClassIndex(classIndex == -1 ? wekaInstances.numAttributes() - 1 : classIndex);

        try {
            classifier.buildClassifier(wekaInstances);
        } catch (Exception e) {
            throw new FOSException(e.getMessage(), e);
        }
    }
private void trainClassifier(int classIndex, Classifier classifier, Instances wekaInstances) throws FOSException {
        wekaInstances.setClassIndex(classIndex == -1 ? wekaInstances.numAttributes() - 1 : classIndex);

        try {
            classifier.buildClassifier(wekaInstances);
        } catch (Exception e) {
            throw new FOSException(e.getMessage(), e);
        }
    }
Trains the given {@code classifier} using the given {@link com.feedzai.fos.impl.weka.config.WekaModelConfig modelConfig}
and {@link weka.core.Instances wekaInstances}.

@param classIndex    The index of the class.
@param classifier    The classifier to be trained.
@param wekaInstances The training instances.
@throws FOSException If it fails to train the classifier.