How to use the Kts ScriptEngine in an IntelliJ IDEA plugin?

Hello, I would like to parse and execute Kotlin kts scripts in my plugin but I am not sure how to get the scriptengine to work. 

I have already tried to bundle the kotlin-scripting-jsr223 into my plugin which unfortunately did not get resolved in this question.

Is the scriptengine already bundled with IntelliJ? With the following minimalistic plugin, I still get no results:

plugin.xml

<idea-plugin>
    <id>com.mydemo</id>
    <name>MyKtsDemoPlugin</name>
    <vendor>Me</vendor>
    <depends>org.jetbrains.kotlin</depends>
    <extensions defaultExtensionNs="com.intellij">
        <postStartupActivity implementation="MyStartup"/>
    </extensions>
</idea-plugin>

build.gradle.kts

plugins {
    id("org.jetbrains.kotlin.jvm") version "1.5.21"
    id("org.jetbrains.intellij") version "1.0"
}

group = "com.me"
version = "0.0.1"

java.sourceCompatibility = JavaVersion.VERSION_11
java.targetCompatibility = JavaVersion.VERSION_11

repositories {
    mavenLocal()
    mavenCentral()
}

dependencies {
    compileOnly("org.jetbrains.kotlin:kotlin-stdlib")
}

apply(plugin = "org.jetbrains.intellij")

intellij {
    version.set("2021.2.3")
    plugins.add("Kotlin")
}

MyStartup.kt

class MyStartup  : StartupActivity {
    override fun runActivity(project: Project) {
        val scriptEngine = ScriptEngineManager().getEngineByExtension("kts")
        println("ScriptEngine is " + scriptEngine)
    }
}

Output:

ScriptEngine is null