### Question:
BidirectionalMap extends HashMap<K, V> implements Serializable { public K getKey(V value) { return inverseMap.get(value); }  @Override V remove(Object key); @Override V put(K key, V value); K getKey(V value); K removeValue(V value); @Override boolean equals(Object obj); @Override int hashCode();  }### Answer:
@Test public void bidirectionalMapKeyNotPresentTest(){ BidirectionalMap map = new BidirectionalMap(); Object res = map.getKey(1); assertNull(res); }