SpringBoot DefaultValue does not play nicely with Lombok generated constructors

Both Spring and Lombok are commonly used projects.

Lombok has a feature to copy annotations from fields onto constructors. This works great for Spring @Component objects making use of Lombok's @RequiredArgsConstructor, but also needing a @Qualifier on a dependency.

This is currently not possible with Spring, as @DefaultValue is only allowed on ElementType.PARAMETER.

Allowing @DefaultValue on an ElementType.FIELD would enable immutable ConfigurationProperty objects with default values.

A sample class using a manually maintained constructor:

package com.example.demo;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import org.springframework.boot.context.properties.bind.DefaultValue;

@ConstructorBinding
@ConfigurationProperties("app")
public class DemoConfigurationProperties {

    public DemoConfigurationProperties(@DefaultValue("default!") String property) {
        this.property = property;
    }

    private final String property;

}

Allowing the default value annotations would enable a lombok.config consisting of:

lombok.copyableannotations += org.springframework.boot.context.properties.bind.DefaultValue

and the above class written more concisely as:

package com.example.demo;

import lombok.RequiredArgsConstructor;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import org.springframework.boot.context.properties.bind.DefaultValue;

@ConstructorBinding
@ConfigurationProperties("app")
@RequiredArgsConstructor
public class DemoConfigurationProperties {

    @DefaultValue("default!")
    private final String property;

}

This would be more useful in configuration classes that contain more than one property.

Comment From: wilkinsona

This is a duplicate of https://github.com/spring-projects/spring-boot/issues/20402.