Java – groupingby with collectingandthen – is there a faster / better / cleaner way?

I have the following courses (getters):

public class AlgorithmPrediction {
    private final String algorithmName;
    private final Map<BaseDatabaseProduct,Double> productsToAccuracy;
}

Now I want to create a mapping from the collection populated by the algorithmprediction object, with algorithmname (unique) as the key and productstoaccuracy as the value I can't think of anything more complicated than this:

algorithmPredictions.stream()
.collect(
        groupingBy(
                AlgorithmPrediction::getAlgorithmName,Collectors.collectingAndThen(
                        toSet(),s -> s.stream().map(AlgorithmPrediction::getProductsToAccuracy).collect(toSet())
                )
        )
);

This can't be right What did I miss? thank you!

Solution

algorithmPredictions.stream()

algorithmPredictions.stream()
                    .collect(toMap(AlgorithmPrediction::getAlgorithmName,AlgorithmPrediction::getProductsToAccuracy));