Precompiled Script Plugin unable to reference classes provided by 3rd party plugins

I have a conventions plugin (a precompiled script plugin) which;

  • includes the openapi generator gradle plugin
  • registers a custom task using the org.openapitools.generator.gradle.plugin.tasks.GenerateTask that the openapi generator plugin provides.

It looks something like:

plugins {
  id 'org.openapi.generator'

task openApiGenerateClient(type: org.openapitools.generator.gradle.plugin.tasks.GenerateTask){
    generatorName = "java" //
    inputSpec = "$projectDir/openapi.json"
    outputDir = "$buildDir/generated/client"
    invokerPackage = "${}.openapi.client"
    apiPackage = invokerPackage
    modelPackage = invokerPackage
    configOptions = [
            "dateLibrary": "java8",
            "library": "resttemplate",

however I get an error saying ‘org’ is an unknown property when I attempt to build;

> groovy.lang.MissingPropertyException: Could not get unknown property 'org' for project ':openapi' of type org.gradle.api.Project.

Any ideas?

I am able to provide a custom task from my project’s build.gradle (outside of the precompiled script plugin – but I really need to register the custom task inside the conventions plugin).

My precompiled script’s build.gradle looks something like:

plugins {
  id 'maven-publish'
group = ''

repositories {

dependencies {
  implementation 'org.openapi.generator:org.openapi.generator.gradle.plugin:5.3.0' //

Can you priovide an MCVE?
Like you showed it, it will not even build but fail with complaining about implementation in the build script.
An if I add the proper plugin, it works just fine.