[FEATURE] Value annotation should use already defined private constructor

[DevQuandt]

Describe the feature
When I use the @value annotation with staticConstructor = "of" and a private Constructor is already defined, Lombok should use the private Constructor to generate a static of Constructor.

Lomboked version

@Value(staticConstructor = "of")
public final class SampleDocument {

    private final String value;

    private SampleDocument(final String value) {
        assertThat(value).isNotEmpty();
        this.value = value;
    }

}

Java version

public final class SampleDocument {

    private final String value;

    private SampleDocument(final String value) {
        assertThat(value).isNotEmpty();
        this.value = value;
    }

    public static SampleDocument of(final String value) {
        return new SampleDocument(value);
    }

[...]
}

Describe the target audience
Every programer who want's to do DDD and validate its value objects in the constructor to have only valid domain objects.

Additional context
Currently when a private constructor is already defined no static of constructor will be generated at all.

[rspilker]

I understand the request, and think it is a good idea to generate the static method if staticConstructor is provided, even if we don't generate the (private) all-args constructor.

[rspilker]

If someone would create a pull request with implementations for ecj and javac and create test files in our test infrastructure, this gets higher priority.

[daliclass]

Liked the idea and have have a pull request up for this here #2119

[rspilker]

It's fixed. We just need to add it to the changelog.