### Question:
Dictionary { public void put(K key, V value) { Objects.requireNonNull(key, "Key cannot be null."); DictionaryEntry<K, V> entry = findKeyOrReturnNull(key); if (entry == null) { entries.add(new DictionaryEntry<>(key, value)); } else { entry.value = value; } } Dictionary(); boolean isEmpty(); int size(); void clear(); void put(K key, V value); V get(Object key);  }### Answer:
@Test void testPutWithNullKey() { assertThrows(NullPointerException.class, () -> createDictionaryWithNEntries(0).put(null, 3)); }