### Question:
Result { public static <T, E> Result<T, E> of(T value) { return new Result<T, E>(Objects.requireNonNull(value), null); } private  Result(T value, E err); static Result<T, E> of(T value); static Result<T, E> error(E err); T get(); E getErr(); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString();  }### Answer:
@Test(expected = NullPointerException.class) public void testOfWithNull() { Result.of(null); fail("Should not exec this line : of method should not be able to return the value from null value."); }