[BUG] @lombok.Builder.Default does not work on records

[victorherraiz]

Applying @Defaultto a record class fails to compile.

@lombok.Builder
record Foo (
  // Fails to compile.
  @lombok.Builder.Default String bar = "ok"
) {}

The expected behaviour is that works as in a normal class

• Lombok version: 1.18.30
• Platform: Java 17, IntelliJ IDEA 2023.2.5 (Ultimate Edition)

[mjustin]

Per Lombok author @rzwitserloot's comment on a relevant Stack Overflow question about whether this is possible:

Not right now, I hadn't considered that when extending support of @Builder to records. Unfortunately, I cannot think off of the top of my head of some simple solution to this problem - you can't stick arbitrary expressions in annotations, so e.g. @Builder.Default(System.getProperty("user.home")) doesn't compile - lombok can't do it that way.

Also:

if we do this, probably make you write a static method that produces the value and takes no args, and annotate it with something. For example @Builder.Default, and the name has to be defaultX; if it isn't in that format, you get an error on the annotation explaining how to name them.

An answer to that question calls out a different approach if default values are needed, which is to customize the builder class to set the default value, instead of using @Builder.Default:

@lombok.Builder
record Foo(String bar) {
  public static class FooBuilder {
    private String bar = "ok";
  }
}

[mjustin]

Incidentally, as long as @Default on records is officially unsupported, it would be nice to see that in the @Builder documentation.