SpringBoot Configuration Processor does not support lombok @Builder.Default annotated values

Hi,

Spring Boot configuration processor does not set the default values for those that have the lombok Builder.Default annotation.

Given the following class below, the default value for foo is present but not for bar in the generated configuration metadata.

@lombok.Data
@lombok.NoArgsContructor
@lombok.AllArgsContructor
@ConfigurationProperties
class MyProps { 

  String foo = "default value";

  @lombok.Builder.Default
  String bar = "default value";
}

Comment From: philwebb

Looking at the Lombok documentation for @Builder I don't think we can support @Builder.Default.

They show the following "With Lombok" sample:

import lombok.Builder;
import lombok.Singular;
import java.util.Set;

@Builder
public class BuilderExample {
  @Builder.Default private long created = System.currentTimeMillis();
  private String name;
  private int age;
  @Singular private Set<String> occupations;
}

Getting converted to the following vanilla Java:

import java.util.Set;

public class BuilderExample {
  private long created;
  private String name;
  private int age;
  private Set<String> occupations;

  BuilderExample(String name, int age, Set<String> occupations) {
    this.name = name;
    this.age = age;
    this.occupations = occupations;
  }

  private static long $default$created() {
    return System.currentTimeMillis();
  }

  public static BuilderExampleBuilder builder() {
    return new BuilderExampleBuilder();
  }

  public static class BuilderExampleBuilder {
    private long created;
    private boolean created$set;
    private String name;
    private int age;
    private java.util.ArrayList<String> occupations;

    BuilderExampleBuilder() {
    }

    public BuilderExampleBuilder created(long created) {
      this.created = created;
      this.created$set = true;
      return this;
    }

    public BuilderExampleBuilder name(String name) {
      this.name = name;
      return this;
    }

    public BuilderExampleBuilder age(int age) {
      this.age = age;
      return this;
    }

    public BuilderExampleBuilder occupation(String occupation) {
      if (this.occupations == null) {
        this.occupations = new java.util.ArrayList<String>();
      }

      this.occupations.add(occupation);
      return this;
    }

    public BuilderExampleBuilder occupations(Collection<? extends String> occupations) {
      if (this.occupations == null) {
        this.occupations = new java.util.ArrayList<String>();
      }

      this.occupations.addAll(occupations);
      return this;
    }

    public BuilderExampleBuilder clearOccupations() {
      if (this.occupations != null) {
        this.occupations.clear();
      }

      return this;
    }

    public BuilderExample build() {
      // complicated switch statement to produce a compact properly sized immutable set omitted.
      Set<String> occupations = ...;
      return new BuilderExample(created$set ? created : BuilderExample.$default$created(), name, age, occupations);
    }

    @java.lang.Override
    public String toString() {
      return "BuilderExample.BuilderExampleBuilder(created = " + this.created + ", name = " + this.name + ", age = " + this.age + ", occupations = " + this.occupations + ")";
    }
  }
}

The created field default value has moved into the $default$created() method so we can no longer read it from our annotation processor.

Comment From: a1dutch

@philwebb is there any other way to set the default values that would work with lomboks builder? e.g. via some annotation or calling the $default methods

Comment From: philwebb

I can't think of one. I don't think we can call methods during annotation-processing.