### Question:
SimpleObjectId extends BaseObjectId { @Override public int hashCode() { return id.hashCode(); } SimpleObjectId(Object id); @Override Object get(String attributeName); @Override Object get(); @Override int size(); @Override String toString(); @Override boolean equals(Object object); @Override int hashCode();  }### Answer:
@Test public void testHashcode() { SimpleObjectId id = new SimpleObjectId(100); assertEquals(id, id); assertEquals(new SimpleObjectId(0), new SimpleObjectId(0)); assertEquals(new SimpleObjectId(""), new SimpleObjectId("")); assertNotEquals(new SimpleObjectId(1), new SimpleObjectId(-1)); }