Rolling out @Nullable

Rolling out @NullableWe’re helping the type system to help you to help your customers Lots of us have strong opinions on null. I don’t think it’s evil, or that using null is sloppy. I just want to be deliberate: wherever a parameter or return value can be null, the interpretation of that should be explicit. /** * Consumes the next line of text and returns it. * Returns null if there are no more li