@Test
 public void testHashCodeDifferentTopLeftCorner() {
   assertNotEquals(
       HASH_CODE_MUST_BE_DISTINCT,
       built.hashCode(),
       builder.setTopLeftCorner('x').build().hashCode());
 }
 @Test
 public void testToStringDifferentTopLeftCorner() {
   assertNotEquals(
       TO_STRING_MUST_BE_DISTINCT,
       built.toString(),
       builder.setTopLeftCorner('x').build().toString());
 }
 @Test
 public void testNotEqualToDifferentTopLeftCorner() {
   assertNotEquals(
       NOT_EQUAL_TO_INSTANCE_WITH_DIFFERENT_VALUES, built, builder.setTopLeftCorner('x').build());
 }