Password extends AbstractSimpleDatatype<String> { public static Password valueOf(String value) { if ((value == null) || (value.isEmpty())) { return null; } return new Password(value); } protected  Password();  Password(String value); @Override String toString(); static Password valueOf(String value);  }
@Test public void testNull() { assertThat(Password.valueOf(null)).isNull(); assertThat(Password.valueOf("")).isNull(); Object value = AbstractSimpleDatatypeBase.getValue(null); assertThat(value).isNull(); }