@Test
  public void testHash() {
    PwFloor floor1 = (new Gson()).fromJson(floor_2_resources, PwFloor.class);
    PwFloor floor2 = (new Gson()).fromJson(floor_3_resources, PwFloor.class);
    PwFloor floor3 = (new Gson()).fromJson(floor_2_resources, PwFloor.class);

    assertEquals(floor1.hashCode(), floor1.hashCode());
    assertNotEquals(floor1.hashCode(), floor2.hashCode());
    assertNotEquals(floor2.hashCode(), floor1.hashCode());
    assertEquals(floor2.hashCode(), floor2.hashCode());
    assertEquals(floor1.hashCode(), floor3.hashCode());
  }