Method apply

app/src/main/java/androidx/paging/DataSource.java:188–195

(@NonNull List<X> source)

            final @NonNull Function<X, Y> innerFunc) {
        return new Function<List<X>, List<Y>>() {
            @Override
            public List<Y> apply(@NonNull List<X> source) {
                List<Y> out = new ArrayList<>(source.size());
                for (int i = 0; i < source.size(); i++) {
                    out.add(innerFunc.apply(source.get(i)));
                }
                return out;
            }
        };
    }