MapIdField { public boolean containsMapId(String mapId) { return mappedObjects.containsKey(mapId); } MapIdField(); void put(String mapId, Object value); void remove(String mapId); Object get(String mapId); boolean containsMapId(String mapId);  }
@Test public void testContainsMapId() { mapIdField.put("aMapId", "aMapIdValue"); assertTrue(mapIdField.containsMapId("aMapId")); assertFalse(mapIdField.containsMapId(null)); }