if (implementationClassNames.add(implementationClassName)) {
                        try {
                            Class<?> implClass = classLoader.loadClass(implementationClassName);
                            if (!serviceType.isAssignableFrom(implClass)) {

        then:
        type == TestPlugin1
    }

    private URL writePluginProperties(Class implClass) {
        def props = new Properties()
        props.setProperty("implementation-class", implClass.name)
        def propertiesFile = testDir.file("${implClass}.properties")
        propertiesFile.getParentFile().mkdirs()
        GUtil.saveProperties(props, propertiesFile)

        String implClass = 'my.MyPlugin'
    ) {
        file("$targetBuildName/build.gradle") << """
            plugins {
                id("groovy-gradle-plugin")
            }
            gradlePlugin {
                plugins {
                    test {
                        id = "$pluginId"
                        implementationClass = "$implClass"
                    }
                }

        String name,
        Class<T> implClass,
        Action<BuildServiceSpec<P>> configuration = Actions.doNothing()
    ) {
        return registry.registerIfAbsent(name, implClass, configuration) as RegisteredBuildServiceProvider<T, P>
    }

    private buildFinished() {

            //
            // Add factory method
            //
            publicMethod("load", RETURN_OBJECT_FROM_STRING, methodVisitor -> new MethodVisitorScope(methodVisitor) {{
                // Call return new <implClass>(param1)
                _NEW(implementationType);
                _DUP();
                _ALOAD(1);
                _INVOKESPECIAL(implementationType, CONSTRUCTOR_NAME, RETURN_VOID_FROM_STRING);

                throw UncheckedException.throwAsUncheckedException(e);
            }
        }

        private static void attachFactoryIdToImplType(Class<?> implClass, int id) {
            try {
                Field factoryField = implClass.getDeclaredField(FACTORY_ID_FIELD);
                factoryField.setAccessible(true);
                factoryField.set(null, id);
            } catch (Exception e) {