### Question:
ReadOnlyProperty { public boolean isNull() { return value == null; } ReadOnlyProperty(Class<T> aType, Object aOwner, String aName, T aDefaultValue); Class<T> getType(); Object getOwner(); String getName(); T get(); boolean isNull();  }### Answer:
@Test public void testIsNullNegative() throws Exception { ReadOnlyProperty<String> theProperty = new ReadOnlyProperty<>(String.class, this, "property", "default"); assertFalse(theProperty.isNull()); }
@Test public void testIsNullPositive() throws Exception { ReadOnlyProperty<String> theProperty = new ReadOnlyProperty<>(String.class, this, "property", null); assertTrue(theProperty.isNull()); }