question: returns copy of keys list . concode_field_sep Map<K,V> valuesByKeys concode_elem_sep Map<V,K> keysByValues concode_elem_sep List<K> keys concode_elem_sep List<V> values concode_field_sep void add concode_elem_sep void add concode_elem_sep K getKey concode_elem_sep K getKey concode_elem_sep List<V> getValues concode_elem_sep boolean containsKey concode_elem_sep int indexOfValue concode_elem_sep String outOfBoundsMsg concode_elem_sep void removeByKey concode_elem_sep void put concode_elem_sep void put concode_elem_sep void remove concode_elem_sep void remove concode_elem_sep boolean containsValue concode_elem_sep void removeExistingEntry concode_elem_sep V getValue concode_elem_sep V getValue concode_elem_sep boolean contains concode_elem_sep void addEntry concode_elem_sep int size concode_elem_sep void addAll concode_elem_sep void addAll concode_elem_sep int indexOfKey concode_elem_sep void putAll concode_elem_sep void putAll concode_elem_sep V get concode_elem_sep V get concode_elem_sep int indexOf concode_elem_sep void removeByValue
target: List < K > function ( ) { return CollectionUtils . copy ( keys ) ; }