### Question:
DateField implements FieldType<Date> { @Override public boolean hasDefaultValue() { return hasDefaultValue; } DateField();  DateField(final Date defaultValue); @Override Types getType(); @Override Date getDefaultValue(); @Override boolean hasDefaultValue(); @Override Date convert(Object objValue); @Override JSONObject toJson();  }### Answer:
@Test public void testHasDefaultValue() { System.out.println("hasDefaultValue"); DateField instance = new DateField(); assertFalse(instance.hasDefaultValue()); instance = new DateField(new Date(0)); assertTrue(instance.hasDefaultValue()); instance = new DateField(null); assertTrue(instance.hasDefaultValue()); }