NullPointerException in equals(), hashCode() and toString() with @Nullable Vector.

[cozycode]

I am creating an Immutable POJO object which needs to support an @Nullable Vector and the toString(), equals() and hashCode() methods are throwing NPEs because they assume the vector will never be null.

Most of the time this isn't an issue because I don't let the Vectors be nullable, but I now have a situation where it is not avoidable. I have worked around it by overriding those three methods, but this is something that I feel should be fixed in the "org.immutables.vavr:vavr-encodings" artifact (i.e. this project).

Thanks for all you do.

[cozycode]

I tried to see if I could fix it and send up a PR, but I don't see where you've done anything custom to support toString(), equals() or hashCode() so I didn't know how to proceed and am less certain if the issue is from this jar. Maybe you need to add something specific to handle those methods? I don't know.

[elucash]

Thank you for reporting this. I definitely want to somehow address the issue, but it might not be easy due to certain limitation we have (regarding annotation matching and handling). It should be possible to customize toString, hashCode, equals using encoding (for that, encoding should contain String toString(), and/or int hashCode() and/or boolean equals(T t) definitions with no annotations, where those would use field(s) and return appropriate values for the type being encoded).

Just as workaround, if you use Vavr it might be more natural to use Option<Vector<T>> x(). Definitely you will not have addX() etc, but Vavr seems to have quite concise construction APIs, it would be quire expressive to have something like .x(Option.some(Vector.of("A", "B", "C"))) or .x(Option.some(Vector.empty().append("A").append("B")...)

On the second thought, it might be even possible (I honestly don't remember if it will work for sure, but...) to create separate encoding for type combination like Option<Vector<T>>

@Encoding
class OptionalVectorEncoding<T> {
   @Encoding.Impl
   private Option<Vector<T>> field = Option.none();
   ... 
   // and then builder which would define `addXx` method by smth like
   // case none -> some(Vector.of(param))
   // case some(v) -> some(v.append(param))`
}

That example is probably for creating encoding for your own needs, I don't know if those belong to this library of basic vavr encodings.

[elucash]

Here's example I found of similar, but probably more involved implementation of the encoding for combined types (apparently those are actually working) https://github.com/Discord4J/discord-json/blob/master/encoding/src/main/java/discord4j/discordjson/possible/PossibleListEncoding.java