Capture Kotlin processor options as custom value

kotlinOptions.gradle

import java.lang.reflect.Field

tasks.withType(getKaptWithoutKotlincTaskClass()).configureEach { task ->
    doFirst {
        buildScan.value "${task.path}.processorOptions", getCompilerPluginOptions(task).collect { "${it.key} = ${it.value}" }.join("\n")
    }
}

static def getCompilerPluginOptions(Task task) {
    def processorOptionsField = getAccessibleField(task.class, "processorOptions")
    def compilerPluginOptions = processorOptionsField.get(task)
    return compilerPluginOptions.subpluginOptionsByPluginId['org.jetbrains.kotlin.kapt3']
}

static Class<?> getKaptWithoutKotlincTaskClass() {
    return Class.forName("org.jetbrains.kotlin.gradle.internal.KaptWithoutKotlincTask")
}

private static Field getAccessibleField(Class<?> clazz, String fieldName) {
    for (Field field : clazz.declaredFields) {
        if (field.name == fieldName) {
            field.setAccessible(true)
            return field
        }
    }

    if (clazz.superclass != null) {
        return getAccessibleField(clazz.superclass, fieldName)
    } else {
        throw new RuntimeException("Field '${fieldName}' not found")
    }
}