/guava/guava/src/com/google/common/collect/Collections2.java
this.function = checkNotNull ( function ) ;
static class TransformedCollection<F extends @Nullable Object, T extends @Nullable Object> extends AbstractCollection<T> { final Collection<F> fromCollection; final Function<? super F, ? extends T> function; TransformedCollection(Collection<F> fromCollection, Function<? super F, ? extends T> function) { this.fromCollection = checkNotNull(fromCollection); <extra_id_0> } @Override public void clear() { fromCollection.clear(); } @Override