### Question:
ConcurrentOpenHashMap { public V remove(K key) { checkNotNull(key); long h = hash(key); return getSection(h).remove(key, null, (int) h); } ConcurrentOpenHashMap();  ConcurrentOpenHashMap(int expectedItems);  ConcurrentOpenHashMap(int expectedItems, int concurrencyLevel); long size(); long capacity(); boolean isEmpty(); V get(K key); boolean containsKey(K key); V put(K key, V value); V putIfAbsent(K key, V value); V computeIfAbsent(K key, Function<K, V> provider); V remove(K key); boolean remove(K key, Object value); void clear(); void forEach(BiConsumer<? super K, ? super V> processor); int removeIf(BiPredicate<K, V> filter); List<K> keys(); List<V> values();  }### Answer:
@Test public void testRemove() { ConcurrentOpenHashMap<String, String> map = new ConcurrentOpenHashMap<>(); assertTrue(map.isEmpty()); assertNull(map.put("1", "one")); assertFalse(map.isEmpty()); assertFalse(map.remove("0", "zero")); assertFalse(map.remove("1", "uno")); assertFalse(map.isEmpty()); assertTrue(map.remove("1", "one")); assertTrue(map.isEmpty()); }