### Question:
AbbreviationMap implements OptionNameMap<V> { @Override public boolean contains(String key) { return get(key) != null; }  @Override boolean contains(String key); @Override V get( String key ); @Override void put( String key, V newValue ); @Override void putAll( Iterable<String> keys, V newValue ); @Override void remove( String key ); @Override Map<String, V> toJavaUtilMap();  }### Answer:
@Test( expected = NullPointerException.class ) public void nullKeysAreIllegalToCheckForContains() { abbreviations.contains( null ); }