FastSafeIterableMap extends SafeIterableMap<K, V> { public boolean contains(K key) { return mHashMap.containsKey(key); }  @Override V putIfAbsent(@NonNull K key, @NonNull V v); @Override V remove(@NonNull K key); boolean contains(K key); Map.Entry<K, V> ceil(K k);  }
@Test public void testContains() { FastSafeIterableMap<Integer, Integer> map = new FastSafeIterableMap<>(); map.putIfAbsent(10, 20); map.putIfAbsent(20, 40); map.putIfAbsent(30, 60); assertThat(map.contains(10), is(true)); assertThat(map.contains(11), is(false)); assertThat(new FastSafeIterableMap<Integer, Integer>().contains(0), is(false)); }