Can't publish a pre-v7 plugin on the portal


I have a plugin I’m working on that has to run on Gradle 5.6.4 which is Groovy 2.x. However, I can’t publish it without setting the website property because it’s rejected by the portal. But, those properties can’t be set on the gradlePlugin block in Gradle 5.6.4. And I can’t compile under 6.x because they aren’t available until 7.6.1. And if I compile it under 7.6.1 it results in this eror:

 > Cannot have abstract method GroovyObject.setProperty().

The theory as to why it does that is that if I compile it in Gradle 7.6.1 which is on Groovy 3 it’s incompatible with 2.x. it’s just not going to work on 5.6.4 if I use Gradle 7.6.1. So I’m stuck. I can’t use 5.6.4 and publish because website, vcsUrl, and tags can’t be set. But I can’t use gradle 7.6.1 because it’s the plugin will not be compatible with 5.6.4.

And no I can’t easily upgrade to 7.6.1 without a huge rework of build.gradle.

So what else can I do to upload the plugin to the portal?