@SuppressWarnings("unchecked")
    @Override
    public <K, V> SortedMap<K, V> getSortedMap(Expression<K> key, Expression<V> value) {
        for (QPair<?, ?> pair : maps) {
            if (pair.equals(key, value)) {
                return (SortedMap<K, V>) groupCollectorMap.get(pair).get();
            }
        }
        throw new NoSuchElementException("GMap(" + key + ", " + value + ")");
    }
Default implementation of the Group interface

@author sasa
@author tiwe
querydsl-core/src/main/java/com/querydsl/core/group/GroupImpl.java