Setters for java.util.Optional Properties do not allow null Values

[buett]

Following example:

@Value.Immutable
@Value.Style(jdkOnly = true)
public interface TestDTO {
    Optional<String> getName();
}

The generated setters in immutable class and builder doesn't allow null values because of using Objects.requireNonNull.

public final ImmutableTestDTO withName(String value) {
    @Nullable String newValue = Objects.requireNonNull(value, "name");
    if (Objects.equals(this.name, newValue)) return this;
    return new ImmutableTestDTO(newValue);
  }

[elucash]

That is correct and is according to design. Use .withName(Optional.ofNullable(null)) or enable implicit and more prone to errors nulls with Style.optionalAcceptNullable = true (then .withName(null) would work IIRC. Thanks!

[buett]

Thanks, it works!
Is there also a possibility to avoid generating the setters with the optional parameter. Optional as method parameter is a pattern which is often discouraged and IMHO there are good reasons for that. Therefore it would be nice to have a switch to turn it off.

[elucash]

Optional as method parameter is a pattern which is often discouraged and IMHO there are good reasons for that.

pls, don't cite the "propaganda" B-) If someone doesn't like optionals, s/he can use @Nullable instead, other than that there are no rational reasons why return value position magically different from parameter or field.

basically, x.withValue(x.getValue()).equals(x) == true should always work, if value is optional or any other type.

[buett]

Who decides what propaganda is? But that's not the point. ;-) Optional as result is a good choice for api description and usage.

I only ask if you could provide a way to turn it off for setters, maybe with a Style attribute.

Automatic property propagation with null values won't work because of method overloading. (Which setter to use?)
And the manually way .withName(null) won't work at the moment. It has to be cast explicitly. .withName((String)null) isn't a nice way and .withName(Optional.empty()) doesn't make it better, I think.

[buett]

I only ask if you could provide a way to turn it off for setters, maybe with a Style attribute.

At least for builders. They don't have getters and so the change has no influence to your rule x.withValue(x.getValue()).equals(x) == true ;-)

[Anusien]

I believe this is possible by setting@Value.Style(optionalAcceptNullable = true)