Custom Generator subclass not found

Description

I'm trying to customize the kotlin-spring generator, using the "subclass" technique described in the customization doc. I tried to use the instructions to generate, applying generatorName = com.example.codegen.KotlinSpring in my gradle settings, but I get the following error:

Can't load config class with name 'com.example.codegen.KotlinSpring'

I overrode getName() and set a breakpoint in my subclass, but it doesn't seem to get called.

I noticed in the original PR to add kotlin-spring that this line was added to META-INF/services/org.openapitools.codegen.CodegenConfig, which looks like determines what generators the config finds.

I'm a bit new to Java, so not entirely sure, but any ideas here?

openapi-generator version

3.3.4

KotlinSpring.java

package com.example.codegen

import org.openapitools.codegen.languages.KotlinSpringServerCodegen

class KotlinSpring : KotlinSpringServerCodegen() {
    override fun toModelName(name: String?): String {
        return super.toModelName(name) + modelNameSuffix
    }

    override fun getName(): String {
        return "haha"
    }
}

Start with docs/customization.md and reproduce the Gradle configuration using generatorName = com.example.codegen.KotlinSpring. Then inspect the META-INF/services/org.openapitools.codegen.CodegenConfig registration and the KotlinSpring subclass to determine why the custom class is not loaded. Done means the subclass is discovered and its overridden behavior is used during generation.