/guava/guava/src/com/google/common/collect/Collections2.java
checkNotNull( action) ;checkNotNull( filter) ;
checkNotNull ( filter ) ;
@Override public boolean retainAll(final Collection<?> collection) { return removeIf(element -> !collection.contains(element)); } @Override public boolean removeIf(java.util.function.Predicate<? super E> filter) { <extra_id_0> return unfiltered.removeIf(element -> predicate.apply(element) && filter.test(element)); } @Override public int size() { int size = 0; for (E e : unfiltered) {