What is the best way to document Groovy class properties if Javadoc's @param tag doesn't fit?

Question

I have a Groovy class definition which looks like the following:

package packageC;

import packageA.ClassA1;
import packageA.ClassA2;
import packageB.ClassB1;

class BuildConfig implements Serializable {
    String projectId;
    String dockerComposeFile = "docker-compose.yml";

    // dozens of other properties elided...

    def prepare() {
        // performs some setter-like post-processing
    }
}

As I understand, GroovyDoc uses Javadoc-style comments to generate documentation. However, the @param tag only applies to methods. Since there is no explicitly-written constructor for this class, I'm not sure how to document the properties.

Question: what is the best way to document Groovy class properties?

I should add that this project/repository is not currently connected to a GroovyDoc generation service (neither CLI nor Apache Ant). However, if I am writing comments, then I might as well do it "the right way" (and easily allow GroovyDoc usage in the future).

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I inherited some Jenkins pipeline code and am attempting to document it. I have minimal experience with Java and even less with Groovy. Please excuse any naivety.